If you haven't installed the MMPack, you'll be stuck with older AVI files and Ultimotion.
I looked at MMPack from Theta Band, and I don't think that's the package you are talking about. I looked at MMAudioPack, and that looked more promising, but after applying it, even videos that played before don't play now.
MMAudioPack only has audio ioprocs anyway, but if lack of audio support was preventing me from playing videos, then it might have fixed it.