@TC - to which I think should be added (1.5) not lowering the collective super-gently and testing for stability if there's even the slightest doubt about stability, or even if not.
You guys all have at least 10x the heli time and experience than I do, but this point seems kind of basic.
After hesitating for ages and clearly being uncomfortable with the landing, he then (I interpret, from the video) dropped the collective. Heli whaps back onto tail, cyclic shoved forward, residual lift brings nose up but then runs out, heli whaps back even harder, most likely breaking the tail rotor. THEN he yanks the collective, but since there's no tail rotor any more, it whips round (as we see from the one frame with the nose visible) and the rest follows.
Very sad. And amazing that it happened to someone with 25K hours. But then, it always is.