Macbook pro problems with .mov files

More than a month ago all of my .mov files disappeared. I have been using the same laptop, the same Canon 7D for filming movie clips, all the same software for a year and a half. The thumbnail is black. They will not play in either Quicktime or VLC. Quiktime says, "A necessary data reference could not be resolved" VLC just lists the file then does nothing. I can not download any photos from my camera to Aperture, iPhoto won't download any files that come after a video clip and I managed to corrupt a friend's memory stick because I clicked on a .mov file he had on it. Both my Mac and 2 windows computers said the drive was unreadable. My computer current on software updates. I took it to the help desk at my son's school (supposedly authorized Apple service) and they tried to repair the permissions, but it didn't do any good. Luckily most everything is backed up with Time Machine, but I'm afraid to do any new backups and corrupt the drive. I'm getting more and more items in need of back up. Any suggestions? MacBook Pro, 10.6.8