Capture a photo

Which system versions running on your Mac?

• On macOS 12 Monterey This will work: How to extract a still frame from a video in Photos 7 on macOS 12 Monterey https://discussions.apple.com/docs/DOC-250004312
• On macOS 11 Big Sur it is more involved: How to extract a Still Frame from a Video Clip in Photos 6 in Big Sur
• In the earlier versions of Photos we could use the actions menu in the video controls to save a selected frame as Tiff to to the Pictures folder: click the gears icon in the video controls, select "Export frame to pictures", then open the Pictures folder in the Finder and look for a TIFF file.

The easiest way is to pause the video and then take a screenshot.