I downloaded all of the requirements for BitComet (even the movie player) but when I downloaded a movie it used QuickTime and now I don’t know how to switch it to use the movie player. How the h*** do I switch it?! I even tried re-downloaded BitComet.
BitComet is a file-transfer program. It’s like FedEx or UPS, it just delivers stuff. If what gets delivered is the wrong stuff, that’s not FedEx’s fault. Once whatever-you-asked-for is downloaded, BitComet’s job is done.
Your system setup, and specifically your system’s file associations, determine what application gets used to open what kind of file. None of that has anything to do with BitComet at all.
Video players, during their setup phases, usually offer a choice about which file extensions to associate with them. If you don’t pay attention to this, many of them grab as many different sorts as they are capable of playing. This apparently happened to you when you installed QT.
Reinstall the player you think your system should have used, and this time be careful about the file associations. You should almost never take the default options for installation. Take the advanced options, even if you don’t change any of them, so you’ll at least know what happened. This is usually where the file association changes are made.