Dude saw the moment is head got sliced in half.
as The_Jerk has already mentioned - the rotor assembly was pitched forward. since there is no further information on this one we will never know the reason for that. only STRONG headwinds may cause a helicopter pilot to do so. but there's clearly not enough of that at that landing zone as you can see by the clothes and hair of bystanders and the trees in the background. maybe it was some feet above the ground which is not uncommon. but it's clear that the guy walking towards to the heli has no clue of anything about helis by the way he is approaching it. at least the pilot should have noticed that as well and it's partially his fault too. that's the exact reason why authorized people tell you to duck if you're leaving or approaching a running helicopter. it's like slowly crossing a six lane highway without any looking. or it is much easier to explain than we've all expected: he was a chimp or indian.