Because of the content you have to sign up and create an account with Youtube. I would think some people are not willing to open an account. I know I am not. Sorry.
Open it and see. I just tried it again and it gives you a message that states that there is adult content involved and you have to open an account showing that you are over 18. Too much trouble.
Maybe others will have better luck. Thats why I said try it yourself and see what happens. Maybe there is something related to my IP address that blocks me from opening it. I think it is the site, but what do I know. I am not an IT geek so these things sometimes elude me.
Saw it a few days ago- the adult content is because of some people getting seriously hurt doing stupid things- lots of Darwin Award contenders, so they dont want young kids viewing it and trying to copy stuff.
Working my way through his uploads, there are loads of great fail compilations.