What Is This Pianist Doing?

Here's another of my "What is This Pianist Dong?" series clips. Here we have something that looks .. well, almost unplayable. It's very fast. But take a look here. Forget about the right hand for a moment and watch the left. It's the key to the whole piece.

So, what's being done here? The composer is creating a harmonic background pure and simple. Yes, it's sophisticated technically, but it's just a background nonetheless.

Then, the right hand plays an equally impressive melody.

This goes on for a while. Then, at about 1:40, a new section is introduced giving contrast. The pianist plays this and back again to the original pattern.