Google has updated their embeddable player to add support for more features.
Users now get more options to load multiple videos through a list in the embedded video player.
The first change of note is the syntax for embedding the player in an HTML document. As for single-video playback, you can use the iframe embed code to load a list of videos, and the IFrame embed supports HTML5 video playback in environments where Flash is not available. Another exciting change relates to the lists of videos that you can load. The player is no longer limited to just displaying videos from an actual YouTube playlist. You can also load a user’s uploaded videos, a user’s favorite videos, or videos matching a specific search term. In the embed URL, the listType and list parameters control the list of videos that is loaded. The listType value can be either playlist (the default), user_uploads, or search. Depending on the listType value, the list parameter value should be set to the desired playlist id, YouTube user ID, or search term.
Here is a sample page that you can use to play around with the settings.