Well about the 2 handed tapping as its called, its beacuse you can techinically in that part of Jordan, the solos, strum once and just hit everything in order without strumming, so, because its coming so fast, strum once, move both hands to the buttons and just hit everything and if you miss, restrum and start over.
But to be able to do it in most songs is hard. Never mind the rainbow of notes that comes down that fast in Jordan.
I play GH1/2 a lot, im ranked about 750th in the world on scorehero, im definatly not great, but im pretty good, and this guy could probably beat me with his eyes closed.