Use NumPad keys to step by frame(60/30 fps), make screenshot, flip horizontally.
NumPad keys:
[ * - flip horizontally ]
[ 7 - enable / disable ] [ 8 - hide canvas ] [ 9 - make screenshot ]
[ 4 - change step size 1/2/4 ] [ 5 - step left x3 ] [ 6 - step right x3 ]
[ 1 - pause / play ] [ 2 - step left * size ] [ 3 - step right * size ]
Press 7 to enable, move by pressing 2/3, make screenshot by 9.
Key 8 is used if video source cannot be used as source/for manipulation/saving(due to cross-origin restrictions). Right click on canvas to download image manually.