Peanut Gallery: The Online Interactive Multi-User Movie Viewer, for Mac OS X. Chat client plus video player equals online MST3k. It even has robot silhouettes avatars!

Multiple participants can watch a DVD, but everyone must have a local copy of the DVD. The DVD video does not stream from one chat client to another.

Almost making up for it, if two people want to watch a video hosted on the Internet, then both clients can stream or download directly from the Internet site. The Internet video does not stream from one chat client to another.