Just wanted to explain antboy's comment a bit more.
Quicktime (like AVI) is a Container, which means that it's just a way of "wrapping" codecs (compression formats) so that they can be used in a standard way by programs. You can think of a container in the same way as those metal boxes that you see piled up on cargo ships. To the shipping operator, it doesn't matter what's in them. They're all the same size, and they all have the same mechanism to mount them, whether on a ship, a truck or a train.
Insider the container, you can have quicktime, MPEG, H.264 etc, so this is what we would need to know to see why your system isn't working.
Download a tool like Mediainfo, and put its report in the body of your next post.