Question: Which ad formats are not available on mobile devices?
- Non-skippable video ads.
- Bumper ads.
- Skippable video ads.
- Overlay ads.
Explanation
This format is not available on mobile because it is defined as a legacy placement that appeared on desktop only. Overlay ads sat on top of the video player rather than playing as an in-stream video unit. YouTube moved away from this format to prioritize ad experiences that work better across desktop and mobile environments. Mobile inventory instead supports video-first formats that fit the YouTube player experience on phones and tablets.
Why the other options are incorrect
Non-skippable video ads are in-stream video formats and can serve on mobile devices.
Bumper ads are short in-stream video formats designed to run across mobile and desktop inventory.
Skippable video ads are in-stream formats and are available on mobile devices.
Source for verification
YouTube Help: YouTube advertising formats support.google.com
Google Ads Help: About video ad formats support.google.com
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