As VLC offers instantaneous pause and allows playback in frames, as you
can see here. You might need to take a snapshot of either specific frame
or an instant paused frame. Guess what? VLC lets you take screenshots
as well. You can capture a frame either by pausing the video, or while
playbacking video frame-by-frame. To take snapshot more promptly assign a
hotkey to snapshot feature from VLC Preferences. Otherwise from Video
menu, click Snapshot to capture a screenshot of a frame.