Google Ads help documentation published for Video campaigns describes a Lookalike targeting model that keeps the narrow, balanced and broad reach tiers the company stripped out of Demand Gen in March 2026, leaving one audience product running on two different sets of rules.

In short

Google's help documentation now describes how to build Lookalike segments inside Video campaigns, a targeting product that was previously documented for Demand Gen alone. The three reach settings, narrow at 2.5 percent of users in the target location, balanced at 5 percent and broad at 10 percent, still apply in the video surface, even though Google converted that same tiered control into audience suggestions for Demand Gen in March 2026. If you run YouTube brand campaigns, your first-party lists can now seed audience expansion inside that buying surface, subject to a documented minimum of more than 100 matched people.

A help page, not a blog post

The change surfaced on September 1, 2026, when PPC News Feed reported that Google Ads was extending Lookalike segments to Video campaigns. There was no accompanying entry on the Google Ads and Commerce Blog and no email to advertisers. What exists is a Google Ads Help Center article titled "Use Lookalike segments in Video campaigns to grow your audience," spotted by Hana Kobzová.

The page carries a note near the top defining the current scope of the product. According to Google, "Lookalike segments are only available for Demand Gen and Video brand campaigns."

That single sentence is the substance of the change. Until this documentation appeared, the public help material and the Google Ads API reference described Lookalike segments as a Demand Gen feature. The API documentation still frames them that way in places. Video brand campaigns had been referenced as a lookalike-capable surface once before, in February 2026, but only in passing and only to say what a separate change would not affect.

How the segments are assembled

The mechanics documented for Video campaigns match the original Demand Gen construction. A seed list is supplied from first-party data. Google names three permitted input types: existing customer lists, activity on a website and app, and engagement on YouTube content. A customer match list qualifies, as does a list of people who have interacted with an advertiser's site, application or YouTube channel.

From that seed, Google's systems identify other accounts sharing the attributes of the people on the list. The documentation offers a worked example involving an advertiser looking for players of strategy-based games, who uploads an existing customer base and receives a segment of other strategy gamers matching the attributes in the seed audience.

Segments refresh automatically. According to the documentation, the refresh runs every one to two days against available customer data, which means the composition of a live audience changes without advertiser intervention.

Three tiers, expressed as a share of the target location

The reach model is the part worth reading closely, because it is the part Demand Gen no longer has.

Narrow segments are populated with approximately 2.5 percent of users in the ad's target location, producing the tightest similarity to the seed. Balanced, the default, aims for 5 percent. Broad targets 10 percent, and Google states plainly that the widest tier may include users less similar to the seed than the other two options produce.

These are not soft guidelines in the video context. They are the boundary of who the campaign can reach through the segment. In Demand Gen, that boundary no longer exists. Google converted Lookalike segments there from strict targeting constraints into audience suggestions in a change documented in February 2026 and effective the following month, replacing the percentage ceiling with a directional signal fed into its models. At the time, the company's own FAQ was explicit that the conversion applied to Demand Gen alone and did not touch lookalike audiences on other campaign types such as Video brand campaigns or Display & Video 360.

Six months later, the video documentation confirms that separation held. One product name, two behaviours, and no shared control surface between them. An advertiser running both campaign types now has a segment that functions as a hard cap in one and as a hint in the other, while both report performance in a row labelled Lookalike.

Minimums, statuses and a three-day lag

The size requirement documented for Video campaigns is modest. The sum of all submitted seed lists must be over 100 active matched people. Below that line, the segment is not available for use.

Enforcement is not instant. According to Google, it can take up to three days for a Lookalike segment to reflect a failed seed list requirement and stop targeting potential customers. During that window, a segment that no longer meets the threshold continues to serve.

Four states are documented for a segment: populating, complete, seed list too small, and inactive. The requirements section of the same page also refers to a failed state. Status is visible in Audience manager, reached through the shared library drop-down inside the Tools menu, under the data segments tab. Google adds a caveat there that matters for anyone reconciling numbers mid-flight: ad group serving can begin before reporting reflects it, because the two systems are not always synchronised.

A number that does not match

The two documents describing this change do not agree on the threshold. The Google help page attached to this report states the requirement as more than 100 active matched people. The September 1 write-up states that Google recommends at least 1,000 active users in the seed list for better audience quality, and recommends value-based data where available. Neither the 1,000 figure nor the value-based data recommendation appears in the help page text.

Both figures have precedent. Google's API reference for lookalike audience segments has carried a 1,000-person minimum in one version and a 100-person minimum in another. The wider trend runs toward the lower number: Google cut audience targeting minimums to 100 users across all networks in a change documented in December 2025, a sharp reduction from the 1,000 active users previously demanded on Search. The distinction between a hard requirement of 100 and a quality recommendation of 1,000 is doing real work here, and the published help page states only the former.

Where the segment can be built, and where it cannot

The creation path is constrained in ways that will shape account structure.

A Lookalike segment for a Video campaign can only be created in the audience section of the ad group settings page, during campaign creation. The workflow runs through the Audience card under the Ad group section, into the Lookalike segment drop-down, then a new segment panel where a name, at least one seed list, target countries or regions, and a reach setting are entered. Up to 10 seed lists can be attached, and segments can be built from as many as 10 existing audience lists.

Once created, the segment is visible in Audience Manager. It cannot be modified there. According to Google, "they can't be deleted or edited in Audience Manager." Existing segments can be added to later campaigns, either as an inclusion or, through the exclusions drop-down, as an exclusion.

Google also flags a lead time. The documentation states that data collection takes time after a campaign is created, and that segments built two to three days ahead of serving are more likely to be ready when the campaign starts. For advertisers accustomed to putting a campaign live on the day of a client brief, that is a scheduling constraint rather than a footnote.

The portability problem

The most consequential restriction concerns audiences that travel across campaign types. If an audience segment contains a Lookalike segment and is applied elsewhere in the account, Google shows it as "Eligible - Limited" for other campaign types. The rest of the audience segment stays intact and continues to work; the lookalike component does not.

The stated reason is a direct contradiction of the note at the top of the same page. According to the documentation, "Lookalike segments can't be used outside of Video campaigns." The scope note says Demand Gen and Video brand campaigns. The portability note says Video campaigns only.

The likely explanation is that the sentence was written for a Video-specific article and not reconciled against the product's wider availability. It is not a trivial editing artefact. Advertisers reading the page to work out whether a segment built for a video flight can be reused in a Demand Gen campaign will find two answers on one screen, and the "Eligible - Limited" label they see in the interface will not tell them which one applies to their account.

Reporting and insights

Reporting requires no separate apparatus. Because a Lookalike segment is a segment, it reports through the standard segment reporting features, reachable either from the Campaigns menu through the reports table and the performance summary submenu, or from the Audiences view under the audiences, keywords and content drop-down.

The insights layer is more granular than the reporting. Segment composition can be broken down by affinity categories, in-market categories, age, gender, geography and devices, viewed through Audience manager under data segments. That breakdown is the only window into who a segment actually contains, given that the segment itself is machine-assembled and refreshed on a one-to-two-day cycle.

What Google tells advertisers to feed it

Three practices are documented on the page, and each one says something about how the model behaves.

The first concerns seed quality. Google directs advertisers toward seed lists made up of the users most similar to recent converters, including frequent purchasers and people who came close to converting. The second extends the seed beyond owned channels: users who engaged with a brand on external media channels are to be added to the same segment as recent converters rather than kept separate. The third is structural. Google recommends pairing a Lookalike segment with a high-intent custom segment in the same ad group, built from 10 to 15 of an advertiser's top converting search terms.

That last point connects video prospecting to search demand data, and it is the clearest signal of how Google expects the two segment types to interact inside a single ad group.

Why this lands now

The video surface has been accumulating audience infrastructure for two years, and the pieces arrived from several directions.

In August 2024, remarketing based on viewers of specific YouTube creator videos appeared without announcement, extending list-building past an advertiser's own channel. Display & Video 360 expanded its audience reporting taxonomy in November 2025 to include Lookalike as a distinct classification. From June 15, 2026, DV360 replaced legacy audience expansion with lookalike audiences for YouTube Video reach and Video view campaigns, with no automatic migration of existing settings.

Google Ads Video campaigns were the outlier. The documentation closes that gap and puts the same audience construction in front of buyers working in Google Ads rather than the demand-side platform.

The plumbing underneath moved too. Customer Match uploads through the Google Ads API stopped working on April 1, 2026, forcing programmatic list management into the Data Manager API. Any team that has not completed that migration has no route to build the seed lists this feature consumes.

What it means for media buyers

For advertisers running YouTube brand campaigns, the practical effect is that first-party data now produces a controllable prospecting audience inside the same campaign type used for reach and consideration buying. Until now, expanding beyond a known list in Video meant audience expansion or optimised targeting, neither of which exposes a similarity ceiling.

There is a compliance dimension that does not appear on the help page. Lookalike segments are classed as advertiser-curated audiences in Google's personalised ads policy, and in June 2026 the company documented that campaigns promoting products in any of 21 sensitive interest categories cannot use them. A campaign in one of those categories that relies on default audience settings may not serve at all. Healthcare, alcohol and financial advertisers extending lookalike prospecting into video inherit that constraint.

The wider context is consolidation. Standalone Display campaigns are being retired and folded into Demand Gen, with the full transition expected to complete by 2027, while Demand Gen itself absorbed a further set of changes in August 2026. Google has also been building the measurement case for YouTube brand spend, globally extending attributed branded searches in Google Ads in June 2026. Placing a controllable lookalike product in Video campaigns fits that pattern: the surface Google most wants brand budgets to move into is the one receiving both the targeting control and the attribution evidence.

The unresolved question is durability. The tiered reach model in Demand Gen lasted from the campaign type's introduction until March 2026 before being converted into a suggestion. Nothing in the video documentation commits Google to keeping the 2.5, 5 and 10 percent thresholds in place. Advertisers building account structures around those numbers are building on a control that has already been withdrawn once, in a neighbouring campaign type, with roughly a month of notice.

Timeline

Summary

Who: Google Ads, advertisers running Video brand campaigns on YouTube, and Hana Kobzová, who spotted the help documentation. The change affects media buyers, performance teams and agencies managing YouTube reach and consideration budgets.

What: Lookalike segments, previously documented for Demand Gen campaigns, are documented for Video campaigns. The segments are built from first-party seed lists of more than 100 active matched people, refresh every one to two days, and offer three reach settings: narrow at 2.5 percent of users in the target location, balanced at 5 percent and broad at 10 percent. Segments can be created only during Video campaign setup, from up to 10 seed lists, and cannot be edited or deleted in Audience Manager.

When: Reported on September 1, 2026. The documentation follows the March 2026 removal of the same tiered control from Demand Gen and the June 15, 2026 replacement of legacy audience expansion in Display & Video 360.

Where: Inside Google Ads, in the audience section of the ad group settings page during Video campaign creation, with status and insights visible in Audience manager under the shared library.

Why: The video surface had been the remaining Google-owned buying environment without a controllable lookalike prospecting product, while DV360 and Demand Gen had both already moved. The change gives YouTube brand buyers a similarity ceiling they did not previously have, at the same time as Google consolidates display inventory into Demand Gen and builds attribution evidence for YouTube brand spend. Two contradictions in the source material, over the seed list minimum and over cross-campaign availability, remain unresolved in the published documentation.