Can you do me a favor and try to make a video. Tell me if it works, without anything extra? I think it's a menu uption under File.
EDIT:
Well, I tested the capture movie feature and it gave the same result, with and without libtheora installed. A 3.3K file, no matter how long I let it run. I guess it's not working yet, so as soon as I get the menu working in kde4, I'm sending it in.