Sitting here studying some statistics – I’m sorry, “quantitative analysis” – listening to and watching a Joe Satriani DVD: Live in San Francisco (2001). I love listening to his music, and enjoy watching him and his band play even more.
Part of my fascination, especially as an amateur piano player, is watching the ease with they play even the most difficult pieces. It is as if their fingers, hands, indeed their whole bodies just know what to do. Of course, my point is exactly that: through extensive training, practice, repetition, and learning from mistakes, the body basically goes on autopilot.
This is not to take away from the performance. Not at all. You can still see the concentration it takes, especially on the difficult ones (they all look difficult to me, but that is beside the point), but it is a comfortable concentration. They are focused on the outcome, not on the playing.
They are having a hell of a lot of fun, and you can tell.