Today I finished the first version of the video playlist for koala (a search engine interface for google, located at http://erstmal.com).

You have a small icon next to every youtube video, which enables you to add the video to the playlist. The playlist is capable of playing all videos in list order but also has a shuffle-button.

Since koala is "AJAX" driven, you are able to continue searching without any interruption in the video playback.