Ok so I have HitFilms 3 Express. I am on windows 10 and I installed Quicktime 7.7.6 on my laptop and when I opened up Hitfilms, it still says that the .mov file is still not supported. Any ideas?
Try and find out the codec. Quicktime is a container and can contain a variety of codecs. Some codecs require FxHome to pay license fees, which is the "Premium Formats add-on."
In the meantime make certain your GPU drivers are up to date, and try disabling Antivirus just to see if it's one of those easy fixes.