Here's a <1.6" 5-shot group from my AK with cheap Tula ammo, std. iron sights and my 50+ year old eyes.
What impresses me about the video is that he simply shot for the middle of the head without a clearly defined aiming point. I don't believe he likely could have resolved the first shot at 100 yards unless he has phenomenal vision.
A 5-shot group would be a lot more convincing that it wasn't a statistical anomaly or one of a large number of tries.
