My brother had a similar accident on the 40 near the 13, except the height was 7-8m where he fell down and nobody saw him. He also somehow landed on grass. People called the police because they saw an abandonned motorbike on the highway. Took a wrong exit by mistake, probably got "surprised" by the curve, half a sec of hesitation... to late.
Lucky to be alived but both legs were fubar, 6 months of rehab to be able to walk. He must be having cold sweats looking at this video.
I've also seen this happening at least 2 times while riding with newbies when accompanying was a thing, no one got hurt but it got me realising how some people just should not be riding motorbikes.