If you don't see a preview for a video within 2 days, the video isn't currently eligible.
We use several criteria, including video topic and content, to figure out what videos can have previews. They may not be added to all videos that are longer than 30 seconds. They're automatically turned on for eligible videos. Video previews are available for most videos that are longer than 30 seconds. They can also see them on watch pages and in search results. Previews are only available on select computer browsers (Chrome versions 32 and up and Opera version 19 and up), as well as in Search on mobile for iOS. Viewers can watch previews on the Home, Subscriptions, and Trending tabs. After the preview plays, viewers see the video's thumbnail. When a viewer hovers over a video's thumbnail on their computer, or scrolls past a video on mobile search, they'll see a 3-second preview. Video previews let viewers see a 3-second preview of your video before watching.
