Its obvious he is not talking about looping because he mentioned stretching.
You need to adjust time without ruining pitch, you can do this by hand, or rather, by ear, but thats hard. There are plug ins that do it for you, or vice versa will change pitch but not time, which you can use to fuck with vocals for example to get a dirty south style.
It just depends on what audio program you are using, I cant comment on anything outside of Pro Tools anymore because well, if its not PT, Im out of the loop (pun intended)
