YouTube's New embedded player

YouTube has launched a new embedded player.
"Does watching a YouTube video on another site leave you hungering for more like it? We just turned on a new embedded player with a scroll-through feature that shows related videos to your embeds. It's fun to play with and lets you discover new, related videos without leaving your site. Just hover over the video after pressing "play" and watch the magic unfold."

The player shows a list of related video.You can watch those videos without opening a new page. This way people watch more YouTube videos without visiting their site.

If for any reason you don't want this option turned on, you can modify the video URL by attaching a rel=0 parameter to the video. i.e. http://www.youtube.com/v/&rel=0

This will make the video play in the old player.