Choppy video while playing MOV file
I've been trying to help a friend figure out a problem with playing MOV videos on her Mac Mini. It is a 2011 or 2012 model. For an unknown reason the videos have a really low frame rate. The audio is OK. VLC Media Player on the same computer plays the videos without any issue. The videos were made using a new-ish iPhone. They play OK on the phone, too. She is using macOS Catalina 10.15.7 and QuickTime Player X. The friend has a large Photos Library with videos in it. If we try playing a video in the library then QuickTime Player is used to play the video and it is choppy. I thought I could just change the default video player to VLC Media Player but it seems that the Photos app uses QuickTime Player to play the video regardless of the default app and there is no way to change that. Or, is there? It seems my two options are to fix whatever is wrong with QuickTime Player or somehow change the player that the Photos app uses. Unfortunately I've found no solutions by Googling about this. What can I do?