Lame fight if it happens but I'll go with the YouTuber and with complete confidence. Ben is literally an all-time worst striker in MMA, or anywhere for that matter. He doesn't know how to box at all, is incapable of throwing a single hard punch, and that's not even getting into his ridiculous technique. He's just a one-dimensional grappler (wrestler) and always has been.
The YouTuber may not be a legitimate boxer but he does at least have some boxing skill to work with compared to Ben and he can punch. Additionally he's the naturally bigger man, has the youth advantage, and is significantly more athletic. This will almost certainly end in a 1st round KO.