Youtube copyright issue help?

i wanna be a youtube partner but im using like music from artists. the music is basically the intro, and it's like 30 sec long from 1 SONG only for all the videos. is that violating copyright rules? i noticed that a utube partner named nigahiga has used many many copyrighted songs from people like beyonce, soulja boy, daniel powter, aly and aj, gwen stefani, the fray, hoobastank and he lypsynched to them. he couldnt possibly contacted all those people right? so im asking if i become a member do i have to remove those videos? they took me a LOONG time to make.. and i got a whole lotta viewers, i dont wanna delete please help me out.. thanks!