Applications :: Quicktime X Won't Play Mov File?

The underlying issue here as well is that iDVD won't recognize this file either.

My wife works for a TV station and one of the editors at the station put a video file together with Final Cut Pro and put it on our external hard drive.

The file is just over 3 gig and won't open in Quicktime. It WILL open in VLC, but I need to get it in a format that iDVD will recognize because I created a DVD menu for this video and want to add it to my DVD project.

I have some other videos she recently brought home as well in the same .mov format but they are smaller, around 800 MB and those will not play in Quicktime either, but they are recognized by iDVD when I try to add a video the DVD project.

I'm guessing I'm missing a codec here and have tried a number of them but nothing seems to work. I was able to find a free converter that converted the file to .avi and it would then open in Quicktime, but there was a logo added to the video which makes it basically useless to us.

So my questions are-

1) Is it simply too big a file for Quicktime to play? What is the max file size it will play?
2) Is there possibly a codec I'm missing here that I haven't tried yet?
3) What else could the problem be?