Nice one!
I liked this simple video. I especially loved the little cat, scrathin' up something wicked. It was definately the highlight of the movie... although the "bouncing" girl wasn't half bad. Just a few suggestions/tips, your movie is a little bit out of center, and perhaps you should make Stephen Hawking not move his mouth. The animation was not to hot for it and remember, that he can't move it anyways! Why not make it so he takes using a little moving line above his head or something... a la "clock"-style. Anyways, I liked this video, keep up the good work.