If say I have a tree in my garden and post a picture of a tree, then it’s reasonable to accept that claim.
If I say I have a unicorn, and post a few seconds of sketchy video from a distance of an animal that looks like might have a carrot stuck on it’s head, then that isn’t sufficient evidence.
This can be summed up as: “extraordinary claims require extraordinary evidence”. And the claim that an individual can play significantly faster, as well as more accurately than anyone else on Earth is an extraordinary claim.
Some close footage of (say), clean tone scale sequences across strings at sensible speeds e.g Al or John Mc speed, with equal clarity and rhythmical accuracy might allow the masses to entertain the claim he can do it 9 times faster as well. FWIW, based on the videos on his Youtube channel, it looked and sounded to me like a few seconds of unsynchronised, inaccurate tremolo picking.