I checked to make sure my export settings hadn't somehow changed themselves since the last time I successfully exported, and it looks like the frame rate did change, but fixing that didn't stop the glitching, just made it run smoother (while glitching). I tried uninstalling the program completely and reinstalling, which didn't help, so I tried uninstalling and reinstalling the previous version of the program, which made it go back to most of the screen being black. So assuming it was something to do with the software, I popped the same video file into the generic video program that came on my PC (climpchamp) and it exported completely fine. Is there something that could be causing the program to have issues with my computer? As I said, my system settings are completely up to date (and everything worked two days ago), but it's obviously working for you, so I don't know what the problem could be.