This machine is equipped with an Anti-rotation device, the jettisonable part of which is attached directly to the Airframe Cargo Hook. This maintains the position of the load in relation to the helicopter and is used for precision construction placement. Prior to the first take-off of the day, the Cargo hook is physically tested in both electrical and manual release modes. Prior to flight, all hook releases are placed in the ARM mode. There is no means of determining if the Load is electrically released, other than functionally testing it after the event. In my experience, virtually all inexplicable Cargo Hook releases are caused by improper rigging setups, eyes hung up on the load beam, sitting on the keeper and slipping off (unless keeperless hooks), or lastly and very rarely, finger trouble.
In this instance, the jettisonable part of the anti-rotation device is released from the hook. It looks intact. There is no visible line or equipment failure.
These instances do happen, but pretty rarely for professional specialty lift operators. The fact that it is worthy of discussion is precisely because of its rarity and the fact it was captured on video.