Can't Stop or Pause mp4 video

[Ralf11]

I am trying to pause a mp4 file (created by my Panasonic camera for focus stacking) - after that I want to extract a frame and save it.

The speeds choice under Playback is grayed out, as is the step commands.

When I hit Play the video completes even if I hit the stop key sequence while it is running.

Thx for your help



macOS 10.13.6