I do not store a lot of videos on my Mac, but I know many of you do. That usually means you have video files in all kinds of different formats. If you have not discovered this already, many older video file formats will not play in macOS Catalina. This article describes why these older videos will not play and also offers solutions in using some generic video playback apps like VLC. VLC is a Swiss Army knife video playback App. It is free and handy to have on your Mac, I have used it for years.