I have installed Myth 2 v1.7.2 straight from a Myth 2 Windows CD using the installer. I am running Ubuntu 11.10. Everything works fine (except it won't run in full-screen mode but that doesn't bother me) but when the game goes to play a cutscene it just crashes - error log below. If I remove the cutscenes folder the game works fine, put it back again and it crashes. I also tried a cutscene folder with just the smk files in them, then just the mov files in them, and then one with both just in case
Myrd will probably be able to help you better, but out of curiosity do the .movs play alright by themselves in your media player? If so, it would rule out that it's a problem with the files, and would also give you an interim solution to watching cutscenes before the level starts.