'Unintentional flight'
Lets be clear, somebody raised the collective. Paasenger fumbling with seatbelts?
My guess is that the cyclic friction was on. Looking at the coning and pitch I wonder if it was running up pre 70%? You wouldn't normally wind it up to 100% until you were ready to lift off. There seems to be lots of evidence to suggest that they weren't ready to go.
An unenviable, and for the pilot potentialy embarrassing situation, a bit like the bloke who lifted up into the bi-fold door in his R44 (and blamed his passenger in his accident report to the FAA...)
It hammers home why we should always remove the duals unless you have a rated pilot in the seat. In my case, my partner completed a 10hr safety course so the duals stay in when she's aboard.
Just the opinions of a non sky-god 800hr R44 owner. I would bet that the pilot in this incident was a low time PPL too??
HP