Visual approach. No big deal?
From what I can see there was no hand flying until AP disconnect at 16:39:37. Why were they flying the aircraft on the automatics when supposedly cleared for the visual approach? Kind of defeats the object of the exercise in my mind. Also this method of flying visuals with the automatics in usually leads to unstabilised and scrappy approaches.
It looks to me like they were coupled to a speed mode viewing the speed vs ROD + configuration in the attached report. This seems to have led to the high rates of descent developing as the drag increased followed by the inevitable GPWS invite to the CP's office. In order to get a handle on the exercise, plan well in advance, get the automatics off, followed shortly after by the FD when cleared for the visual. Not enough hand flying ability, to much reliance on the autopilot and some pretty scary rates of descent close to the ground.
Having said that, anyone can have a bad day.