Right hand spiral descent at very low speed is symptomatic of a low Nr condition with low tail rotor effectiveness and a relatively high collective position.
how do you come to that conclusion?
Seems more likely that following a TR thrust failure, he has lowered the lever to reduce tq reaction and lowered the nose to gain speed.
If you can find a video of an RAF Wessex over a lake in Wales that suffered a TR drive failure, you will see an identical spiral descent.