You Don't See in 4K

At last somebody agrees with me that 120 fps or 250 fps in quake
cannot be smoother than 60fps on a 60 hz monitor.

Bet he gets so much feedback and discussion about this topic, he already regrets making this video.

I don't know about 120 fps on 60hz monitor. It may look the same 60fps@60hz vs 120fps@60hz,
but theoretically you increase the ingame resolution for when moving around.
A 90 degrees turn at 60 fps, renders 15 frames to complete the move,
while 120 fps renders 30 frames. So it may feel more smooth and possibly give better accuracy.
But for the eye it is still the 60 hz from the monitor.