A mov file can contain any number of codecs . Download the free Media Info or GSpot to determine which codecs your file has to see if it is supported by MEP. I use both since the give different info. I think GSpot will tell you if the codec for the file being analyzed is installed while Media Info seems to show more detailed info.
Also if the file is from your digital camcorder or camera, make sure you have the software that came with it installed.