Declared a mayday on the VC 10 with a similar roll but not pitch problem.
We did a 180 and started to descend into thicker air hoping it might help the problem.
In the end I took the autopilot out as we believed the aircraft would break up as the movement was causing ceiling panels to fall down.
I had been taught to always leave it in as it could fly the aircraft better than you Sunny Jim.
Motioned stopped.
Runaway yaw damper but what mystified us is that there was no feed back through the rudder pedals (as we had with the Trident).
The motion was very different to a trident damper runaway.
Trident easier to diagnose as we had damper deflection indicators.
Wasn't the same motion as dutch roll although fairly similar.
Video looks like a rudder deflection problem followed by the secondary effects of rudder -as in roll and thirdly pitch.
Shows how structurally strong SOME aircraft air......