I find this video hard to believe. I would think that any drug that would put a person under so deeply that he wouldn't wake during climax would also prevent him from being able to climax. But getting back to the question of how to sneak a peek. Do you want to keep him as a friend? If you do then don't try to sneak a peek. You'll end up loosing a friend. Best way is be honest and tell him what you want and why. If he's a true friend he'll still be your friend afterwards and you might get to see his bits, but then you might not. Some guys just don't have a desire to show their friends their bits. The majority of my friends have seen mine because I am not a modest type of person. For example, if you come into my room and I have just returned from the shower, then chances are that you will see me au naturel as I will be drying off and dressing. If you see my bits you see them if you don't tou don't, makes me no difference.
Anytime you have to "sneak" to do something, someone's going to get hurt or lose a friend. My advice is don't sneak to do it, just be up front with your friend.