YouTube Fast Search lets you create Playlists Dynamically

Youtube search feature is a little slack, I was wondering when they will let us search videos while a video is still playing.
YouTube Fast Search is a great web application built on the YouTube’s API lets you play videos and search for new videos at the same time. You could also built a playlist from search results and add new videos to the playlist without interrupting it. Asides from the dynamic search, the nice drag and drop interface goes well with the concept.

YouTube Fast Search via Google Operating System