You're seeing Promoted Videos created by YouTube content producers to drive awareness and viewership of their videos.
You may see Promoted Videos on your pages if you have ad units opted in to both text and image ads and are using one of these supported ad sizes:
- 300x250 Medium Rectangle
- 336x280 Large Rectangle
- 728x90 Leaderboard
- 250x250 Square
- 200x200 Small Square
You can prevent Promoted Videos from appearing on your pages by blocking the site youtube.com. This will block all Promoted Videos; it's not possible to block specific Promoted Videos at this time.