Wonder Boy in Monster Land / Wonder Boy II (Sega Master System) - Stages 1-3

[Dostaras]

The "invisibility when hit" issue is caused by the FPS conversion of the final video. You probably recorded it at 60FPS rendered it without any resample and finally youtube converted it to 30 or 29.97 FPS effectively dropping 1 out of every 2 frames.

Since the actuall effect in the game is simply alternating between invisible and visible frames at 60FPS you will either get an "invisible effect" at the end or a "fully visible" depending on the timing of the hit.