There's a good reason why you shouldn't ride a BMX bike down a hill at 50 miles an hour with no helmet. You will crash, and you will eat shit.
Amazingly, this moron managed to make it out without splitting his wig and remains a functioning member of the gene pool. Here's his description of the crash, uploaded to YouTube back in 2012.
I was blasting down this hill like iv done 100s of times but this time my headset came loose and my tire stared swapping side to side and sent me into a speed wabble.