QuickTime in Catalina won't play H.264/AAC video
Trying to help someone who has upgraded to Catalina, but cannot play videos that are created with the H.264/AAC format. The videos work on other Macs running Catalina, so it's not the video itself. Will this require re-installing the entire Catalina OS, since QuickTime is installed with it, or is there some way to reinstall QuickTime by itself. I'm thinking some codec is missing.
MacBook Pro 15”, macOS 10.15