Incredible footage. Really too grainy to tell what is going on. The airspeed does not seem unusually slow for that type, so I wonder if it was some sort of prop control issue. I wish the rudder was clearer, but it does seem to be momentarily at full deflection.
Gives you a bit of perspective at how quick it happens. I remember long time ago doing VMC demos, 5000ft being the lowest allowable height. I can see why.
