Just watch it all the way through. You won't regret it.
I mean, aren't the chick (who barely looks like she's playing btw...) and the middle guy "playing" using the same strings?
I just tried it on my guitar. As far as I can tell, the girl is playing the two middle strings and the middle guy is playing the two highest strings, so they aren't interfering with each other.
I can't seem to find a place where he does. Can you?