In humans, it is very difficult to urinate while the penis is erect. Biological evolution makes it this way so that the urine does not wash away the sperm, thus increasing the chance for procreation.
The next time you have a boner, try to pee. It is hard to get the piss stream started.
Thanks for sharing the clip, but it appears to me that this is just the same orgasm repeated from various camera angles. It's still hot though!