http://www.pprune.org/rotorheads/129...cl-videos.html
If this was seen by a bystander at night, would it appear to be tumbling?
Although it is apparently a hydraulic problem from the hover, it also shows how quickly things can happen. From this, I would guess the recent incident was over in less than 10 seconds, hence my reasoning behind no radio calls.
channel 4 helicopter crashes - YouTube
Vid shows helicopter crash, so please be warned.