I've seen that before - it's amazing he didn't get demolished.
I've also seen videos explaining the death wobble can come from a bike overloaded to the rear; guys will pack a lot of stuff in bags, resulting in a light front and the wobble. They said leaning forward over the tank and shifting your weight to closer to the forks can help get you out of it. That guy's was extreme.
That’s similar to the death wobble in Jeep CJ’s when there’s too much weight in the rear. I experienced it myself in a CJ-5 once when I had three HS friends sitting in the back along with a bunch of camping gear, and we went over a bump. Started the front end shimmying like crazy, but fortunately we weren’t going fast, and a simple stomp on the brakes ended the wobble. It was still scary! After that, I allowed only two passengers in back, and I kept only a small tool chest behind the rear seat, and I never had the issue again.