Dixv is the de-facto version of MP4, since QT 6 comes with MP4 and has the ability to play mp3 files, It works with out a hitch (usually), thats why you need the converter or varifier.
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Divx comes in three flavors, There is the .AVI version, usually these are m$-mp4 formated, and when converted either to acceptable .avi or to .mov divx files. There are .mpg and .mpeg divx files, the .mpg's usually work fine, however the .mpeg versions appear to QT as MPEG2 and there for says you need software, and cannot be converted. Then there are .mov divx, I know many will say that they are just QT files, but I have found many .mov's that have never seen QT. They will play with out a problem, and are also the result of a user who knows that .mov's will play on any system unlike the .avi or .mp(e)g files.
TEG