If you look at video no. 2, I see apparently no aileron movement, but a lot of rudder movement. If ailerons are locked, you can use rudder as a roll control, but it is only a secondary result.
Pitch cannot change so quickly unless you have some kind of pitch control (Trim only??). I flew the 727, and change of thrust gave no initially change of pitch. That was also a secondary result of speed change.
I have tried similar problem - simulated in a little piper - we froze the stick, and had only trim and rudder. It was possible to steer the aircraft, but the handling was exact like we see on this video.
Maybe we should test a frozen stick in the simulator and see how it will turn out?