I think I figured out the stereo thing:
Since the background audience repeats (and is just suspect in general with it roaring at the strangest times), I'm thinking that they must have used some reference audience track, that happened to be in stereo and looped it (stupidly by the way). They then put the vocals over that shyt (which are probably in mono).
Whoever did this spent some time, but got lazy with the background audience
Don't blame the uploader just yet, he could have been tricked by somebody too.