MPEG-4 file compatibility...


I am converting movies using CloneDVD mobile for both iPod and Zen Vision M. Both machines are capable of MPEG-4. So why when I back up a DVD movie for iPod which automatically goes to an MPEG-4 file is it not able to be played on the Creative Zen Vision M also without converting it to .avi?

I would like to be able to backup and convert the movie just once instead of having to do it twice in 2 different formats. Is this possible? And if not, why?