Non-skippable in-stream ads
What are in-stream ads?
Non-skippable in-stream ads are video ads that may appear pre-, mid-, or post-roll while viewing partner content. They can be up to 15-20 seconds long and viewers must watch the ad before they're able to watch the selected video. A companion 300x60-pixel ad unit may be usually displayed alongside YouTube videos that show in-stream ads on desktop. These ads are only available via reservation buy only, and are not available to advertisers via the auction.
In-stream ads are sold on a CPM basis, and may generate higher CPMs than other ad formats on YouTube. Enabling this ad format across your videos can lead to lower video views and watch time. It's up to you to determine the best balance between views/watch time and revenue for your channel, and you can use the Ad Performance and Views reports in YouTube Analytics to help you make that decision.
When do in-stream ads appear?
A host of dynamic signals, including content type and how a user discovered the video, help determine the best time to serve an in-stream ad. When we don't have inventory to display in-stream ads against your videos, we'll backfill with other ad formats.
How are non-skippable in-stream ads different than TrueView in-stream ads?
If a non-skippable in-stream ad appears before a video, the viewer must watch the ad in full before the video will play. With TrueView in-stream ads, viewers have the option watch the ad in full or to skip the ad after viewing it for 5 seconds.