There's a few videos on YT about him, particularly about his newest show and reintroduction to an unaware younger audience who isn't familiar with his tricks. I'd suggest potholer54's critique of the episodes, not only for breaking it down on why Hancock is woo crazy, but also reading the comments where lots of times you get defenders trying their own attempts of logic spin. It's funny and sad at the same time.

I hope Keanu isn't a sucker about this stuff. I believes some of Hancock's ideas too once, but to be fair I was like 11. I can only hope he was playing along and every time Hancock mentions a new fact Keanu goes "whoa..."