YouTube is adding search and 3 other features to embeddable videos. The search feature will appear at the end of videos that are embedded on other sites.
The other features are things you've seen if you visit YouTube's site but were not previously available for the embeds:
- High-quality start images (thumbnails)
- Integrated video annotations
- Integrated closed captions
Google says 44% of their users watch videos embedded on third party sites.