...very respectful video in the first post - unlike some of the amateur and sensationalist coverage elsewhere.
This additional link provides a bit more of the location of the crash:
https://news.italy24.press/trends/636276.html
Wide, open, sweeping curves. Very high speed. Risks from sidewinds coming up or down the gullies - and any detritus on the surface.
.... looks almost like a tragic set of freak circumstances went on. Normally roads are swept prior. The corner and road looks fast and visibility is good. The off road part surprisingly doesn't look that steep (not a vertical drop anyhow) or full of boulders and rocks except for the man-made water tunnel. I guess the police will be interviewing the other rider to help understand more.