Since this TV just didn't seem to match the Notebook theme, I have created a copy of the plain page from the Apple's "Fun" theme and added this TV set to it. You can place over a black background and place your movie behind it. Hopefully Apple won't mind. Get the "Fun Theme Video Overlay" in the downloads section at the top of this page. It's in PNG format because that gave me the smallest file. This is just the 1024X768 version. I'll post more stuff when I get time.
I originally had a suggestion here that said you can "feasibly come up with some crazy stuff, with builds all over the place and with transparent movies placed over other movies, etc. (basically create something that your processor can't play inside Keynote) and if you export the whole thing to an auto advancing QT file it SHOULD actually play correctly since it will all be composited into one movie." Well, with more testing I found this to not be exactly true. While you can do lots of compositing and it will look fine, when you create a slide with builds AND a movie clip on it, when you export it as a self playing movie, the embeded clip will play FIRST and THEN the builds will trigger and come in. Not good.
K2 UPDATE: Compositing now WORKS in Keynote 2. You can now create timmed builds that run over top a playing QT movie and it will export to QuickTime correctly.