I have MEP 14 Plus. I have recorded a movie with my Canon camera. When I uploaded it to my comp. and then to MEP it played the audio but there was no video. I think the file was MOV.
I suspect you do not have the correct video codec for MEP to use for the video - MOV is not a file format but a container file which can have any video/audio codec combination inside.
Do you have Quicktime installed? If not install it and see if this fixes the problem.
If this does not fix it, download and use GSpot to analyse a video clip and determine what codecs are required - the software will also tell you if they are installed.