I don't think it's the engine spooling up - I think it's the decayed Nr recovering when the collective is lowered, once on the water.
The engine winds down in a pefect place to have landed on the deck! Any sooner and they would have been commited to the water (with the slow shallow approach). The captain took the controls off the co-pilot and flew it away from the deck!
The aircraft sank because they hadn't armed the floats
The submerged aircraft got dragged by the seismic array for about 2km.
The guy taking the video (Finnish) just went to work and did his 28 day stint, once rescued
