How much RAM do you have? What video card do you use? I have a 1000 MHz Pentium 3, 312 MB of ram and a Geforce 2 mx 400 with the same distribution, and the movies work fine for me (maybe a tad choppy, but not much).
Maybe you just need more memory.
Edit: I ran those videos at the highest quality. By the way, those movies are really weird!
[ June 09, 2003: Message edited by: Laukev7 ]