Okay, thanks for the info (re seatbelt release).
As I said earlier, I survived one ditching in fixed wing, probably as well-handled as it could be with fixed gear that was going to flip the plane on contact with the water (Otter). I thought maybe with a reasonably controlled auto into the water with a helicopter it might not be that violent. But that's a best-case scenario. So, belts on until motion stops, got it.