YouTube's introduced a new feature into their embed code, allowing viewers to save embedded videos to watch later on youtube.com.
Next time you stumble across a YouTube video that you don't have time to watch, check the upper-right corner. If the video was embedded using YouTube's new iFrame code, you will see a little button that says "Watch Later." When you click that, YouTube will remember that you want to watch the video and let you bring it up later on youtube.com for viewing.
YouTube's Watch Later Feature | Google System via Lifehacker Australia