But how does a dubstep producer make remixes of a song when it's so hard to seperate stuff.

I need some help, i've been looking for this for a long time, still didn't found out, i'd like to try to make a drumnbass remix of this song: Toro Y Moi - Talamak.
Now, the question is, what lot of peaple are having problems whit, is how to I seperate vocals, bass, beat and whatever. I got audacity ...