Although the pilot wasn't in the seat on this occasion, this is strongly reminiscent of the Bell 429 incident in the UK where the helicopter yawed quickly on the ground.
https://www.gov.uk/aaib-reports/aaib...lranger-g-wlts
I wonder if this particular Bell 407 was a later variant with the optional autopilot and a similar yaw channel runaway occurred (which Bell didn't actually "fix" in the 429). Anyone got more detail on the particular version of the 407 involved?