Worried over my son's tapes

mmmm....that's odd!! How old is he? If he is over the age of maturity, there isn't anything you can do, he is pretty much able to do what he wants. But, if he is a young person and lives in your home, i would call him out on it for sure. Don't go at him like gangbusters, but sort of ask about it. How did you come across the tapes? Were you poking around in his room? When you say urinating in his room, is there a bathroom in his bedroom or was he literally pissing in his bedroom, like in a corner or on the carpet? If that is the case, that is your home which means that his bedroom is in your home. You have the right to know. That could cause some serious sanitation issues. Sitting urine can stink after a while and it also goes thru the carpet onto hard wood floors.
If you were poking around in his stuff, he will get angry with you. I would to as he is entitled to his own private space. So you found this tape, what pocessed you to play it? Or did he accidently leave it in the camera? If that is how you found it, it will be real easy to approach him with it.
Just so you know, young people do pose for themselves and they take video of themselves. I used to do it when i was younger with my best gf.
No harm intended for us at the time but maybe he was intending to send it someplace, or post it on You tube or his myspace. Check it out, i would.