I'm having the same issue with munky261. I have a 704 x 396 AVI file, which the built-in Media Player won't play because apparently 396 is not a multiple of 16. Now mplayer does play it, but like in his case, the video is choppy. So choppy in my case, that it's totally unwatchable. Go figure...

The file size is 500+ MB, if that matters.