That video was presented during my 530F initial course at MD back in December. I seem to recall that the cause was a trim runaway, and the pilot became fatigued holding cyclic pressure after flying for some time, and the shop got away from him. Both times I have been to MD for emergency training, I have been given a trim runaway, and had to fly the helicopter back to Falcon Field with the malfunction. They teach you to use your leg, or a passenger, to help hold against the cyclic pressure, and to get it on the ground well before you wear yourself out.