Sampled vs Stealing

I know talking about this topic is like beating the dead horse. Recently, in my ravenous search for the next song to blast in our dorm room and party to, since I'm addicted to finding new music,  I stumbled across a song I knew I had heard before. It just sounded familiar. This song was BEI MAEJOR -- ALL NIGHT. http://www.youtube.com/watch?v=lulIzUsbn-k It turns out after much humming and haaing with friends, we knew that this underground and not-so-mainstream rapper had "sampled" the opening piano riff in the 1981 hit Journey - Don't Stop Believing. http://www.youtube.com/watch?v=rfUYuIVbFg0To be perfectly honest , I love the song. It mixes a solid rock feel to an awesome rap feel.
Another example is the now popular rapper B.O.B - Use Your love.http://www.youtube.com/watch?v=aRHKs_FFZN8 He "remixed" the 80's hit The Outfield - Your Love.http://www.youtube.com/watch?v=ATEUozct-4Y&feature=fvw Both of these rappers sampled these tunes and pulled them off perfectly. I absolutely love mashes and remixes. I just love hearing multiple songs becoming one brand new , sweet tune .
However my issue with it is , what goes on behind the scenes? Does the remixer talk to the original artist and get a green light? Does the remixer pay the original artist? I am just curious. These rappers can easily sample the songs without the real artist ever knowing .They may be underground, but I know how it feels to have someone take credit and the enjoy the benefits on something you have created. Just hearing these tunes spawned the thought. What happens if they didn't get the go-ahead from the original artist?
I would really like to know if these songs make it huge... will we have another Rob Van Winkle vs David Bowie+Freddy Mercury?.. don't know what I'm talking about?... Go search "Vanilla Ice - Ice Ice Baby" on Youtube and "David Bowie and Freddy Mercury - Under Pressure" Listen close.


Just ask Terry or Deaner