Stop. . . . . . . . . . . Esc
Next Frame. . . . . Space Previous Frame. . BackspaceRepeat
When paused in Play(Both) mode, these 'Play' menu options allow you to move forwards or backwards frame-by-frame.
If the 'Repeat' option is checked, the movie returns to the start after moving forward to the end.
After moving backwards to the start, the movie returns to the end.