My guess: he's got a high-IQ, high-functioning, autism spectrum condition.

Sensitive to stimuli like street noise so that he blocks his ears with his hands, obsession and savant-like talent for a specific activity (composing / all things musical), etc.

Maybe I'm wrong, but I think that fairly clearly he's wired a bit different -- and that is a good thing.

Having Asperger's is no status symbol, just a useful diagnosis for parents, schools etc. One of my daughters has high-functioning autism (which Asperger's is a subset of). These diagnoses do mean that the person has at least average intelligence (as opposed to other forms of autism, which can be associated with low intelligence), but it doesn't mean the person is a genius. Of course the geniuses can be very interesting and get more press. I thought the young man in the video did a good job of describing how his mind works, especially in the social arena. For more on Asperger's I would recommend Daniel Tammet's Born on a Blue Day.