These scenes are from season 1 episode 3.
1 minute in the episode, we see Mike Vogel masturbating. There is no full frontal, just his facial expression.
3 minutes in the episode, he is taking a shower and we see his butt when he leaves the shower.
7 minutes in the episode, we get a great view of Adam Demos' butt. Very detailed, we can see the little bit of butt hair he got.