The first indication of anything going wrong is the collective going to full up, followed by a lot of aft cyclic movement. Considering that control movements can usually fit in a matchbox the amount of control travel of both the collective and cyclic could be considered extreme.
Full collective up pulls the engines through blowaway power after the NR droops from 107 to 101, then the NR continues to droop down to about 70% NR. Starting at 130 knots, this would quickly lead to retreating blade stall, accounting for the roll to the left.
Low RPM, the tailrotor is ineffective, airspeed is low and the aircraft yaws to the right since the engines are still trying to get the rotor back to 107 and the torque would be significant.
Thirteen turns to the water at 2.5 seconds per turn, or about 150 degrees per second, similar to a flat spin in an airplane. They kept it upright and pulled the throttles off, not sure why it would have kept rotating and they were unable to regain airspeed.
So why did the collective get pulled all the way up and was left there until the rotor drooped so far? Hydraulics? Servos? Autopilot? Evasive action by the pilots?