Split a movie into clips in QuickTime Player on Mac
You can split a movie into as many clips as you like. After you split a movie into clips, you can rearrange them.
In the QuickTime Player app on your Mac, open the movie you want to split into clips, then choose View > Show Clips.
Move the playhead (the red vertical line) to the place where you want to split the clip (or use the Touch Bar), then choose Edit > Split Clip.
Your movie splits into two clips. Repeat until you have as many clips as you want.
When you’re finished, click Done.