Nr. 1: It's about Jack and his many love interests. Everyone of them gets their own song. There's text in between like 'not that one, how about...' and it ends with Jack/Everyone.
Nr. 2: It's Jack/Ianto. It's played for comedy. I think it starts with Jack coming back after The Year that wasn't. There's lots of dialog cut in between. I think there was one line 'and your momma'. An upbeat song, very catchy.
I hope someone knows these vids. I thought I had it in my favorites, but I didn't have luck. Must have been lost after my last browser crash.