CHR - are you referring to VRS when you talk about rotor stall in a vertical descent with low speed and high RoD?
Only the roots are stalled in Full VRS.
The Blackhawk in the video has forward speed (airflow over the rotor) even in his spiral descent so quite unlikely to encounter VRS.
Rotor stall in a high AoB level turn is something else entirely.
Well said crab. There might be some retreating blade stall if you loaded up the rotor in a steep bank perhaps at high DA.
I am a bit more worried about when he bunts the machine roughly half way through and the rear disc gets awfully close to the top deck. A Bell 429 recently chopped its own tail off in the USA as a result of harsh manoeuvring at low G. Even in a fully articulated (UH60) or semi rigid (Bell 429) you can end up with some weird disc versus fuselage attitudes at low G. Not as bad as an R22 obviously!