The sound on an MOV file can break from several reasons, but the most likely (and the easiest to fix) is simply that the program you are using to play it is incompatible with the file type. MOV files are QuickTime-based files, so trying to play them with a program like Windows Media Player often leads to errors. If trying a player like QuickTime or the free VLC fails, converting the MOV file to another file type is another approach to alleviate errors.
