This is pretty cool. Maybe I'm missing something, but what's the point in the initial genre training? He's taking 185000 samples, and finding similar "looking"

This is pretty cool. Maybe I'm missing something, but what's the point in the initial genre training? He's taking 185000 samples, and finding similar "looking" samples elsewhere in other songs, and then making recommendations based on that. I don't see what that could possibly have to do with genre labels, unless we're under the assumption that finding a match between a Drum & Bass song and one that seems similar with a tag of Trance is somehow a bad match? (which very well could be the case, but seems like a big assumption to make off the bat) Are these recommendations silo'd to the current genre or are they allowed to span genres?