I only offer it if you can't find anything that works for you.
Since Windows Media Player does play these .MOV files why not use that?
What I mean is this. The PC is not actively used so I am guessing you would like to use it, (or already are using it), to show images and play videos in the background in the family room. I think that's a great idea.
WMP can "Shuffle" content. Since you are using Windows 7 I assume this WMP is version 12, the same as mine. If you open WMP and click the ? icon top right, a Help page will open and you can search for "Shuffle" there.
It's possible to shuffle playback of files you point WMP to and the player will happily play those movies, (all file types it can play), continuously.
Play back of images might need some work if they are in the same folder. I'm not sure how that would work.
But you can make WMP go Full Screen which would be just like a screen saver. You would have to set this up each time, and there would be other things to sort out, but then I don't see why it shouldn't work all day until you close the system down at night.
Just a thought.