MacMost: Video Editing

How To Combine Videos On Your Mac
If you need to merge two or more videos into one file, you don't need to do it in iMovie or another video editing app. You can just use QuickTime Player to quickly create a new video file from the original clips.
How To Edit Videos In Mac Photos
MacOS Big Sur adds the ability for you to adjust, filter, crop, rotate and trim videos right in the Photos app, without needing to go to iMovie or Final Cut Pro. You can use the same editing techniques you use for photos, but applied to an entire video.