I haven't seen the full footage as my browser only showed a short sequence of stills BUT from the situation described by HelmetFire, I had a further thought or two.
A sudden and large gust coming from behind a 'hawk in the hover could easily cause a nose-up pitching moment because the airflow over the stab (at the full down position as advertised)would cause the tail to be deflected downwards. The pilot would attempt to correct this by forward cyclic. Because of the low (negative) airspeed the stab would have no input to motor up.
If there had been a loss of yaw control about the same time too, as the aircraft tried to weathercock into wind (ran out of tail rotor authority). In the latter situation it would rotate to the right away from the main rotor direction of rotation. Most pilots sensing a loss of control in the close proximity to a hill (and probably by now also in whiteout conditions if the only visual reference had been lost ) would probably pull a handful of collective in an attempt to fly clear. This would cause the coning angle to increase as described. As the aircraft came round into wind it would be out of trim in pitch (too much forward applied because of the previous attempt to prevent the nose-up pitching). This could easily result in the long probe on the nose striking the hill and the rest is history.
I look forward to the report on this one, I hope we can learn from it. Thank goodness the guys are safe.