Cropping a Video with QuickTime Player

QUICKTIME PLAYER (MAC OS 10.12)

Open your .avi or .mov in QuickTime Player

 

 

To crop, in the top menu go to Edit > Trim...

A yellow frame will appear in the playback control bar. You can grab the ends of the frame and position the ends where you want the clip to start and stop. You can click on the "play" arrow to review.

When you have the selection the way you want, click "trim", then go to "edit > save".

It's useful to save with the same name as the original file, with an additional "cropped" or "final" or "edited" appended to the name. This ensures you aren't saving over your original source video.