Very hard to believe pilots of this freighter sat and watched their jet plunge nearly straight down while not taking corrective action. When descending 2.5 degrees is very noticeable, 5 deg. is a very steep descent, 10 degrees starts filling the ADI with all brown, you only see this in the SIM world. Any airliner heading down at 49 degrees is out of control and will not likely recover without 20K feet and very careful inputs.
When I heard the ATC "pull" I immediately thought someone seen something out front.