Depending on what style of music you are playing, I believe that playing music requires the same understanding of "truth" that actors do. Whether you are replicating or interpreting.
If you're playing a classical piece, like a Mozart for example, you need to understand the emotion is trying to be portrayed, and the "truth" that the author has put into it. This allows you to effectively and appropriately apply your subtleties, ornamentation, articulation, etc.
If you don't do this, you might as well just let a machine play the music.
Likewise with Jazz. A musician's interpretation of a jazz piece relies largely on the musician. What truth he reads from it. What truth from himself he can bring into it. That's why you can take one of the most upbeat standards and turn it into a ballad, or a slow waltz, but you really need a good unerstanding of yourself and your present state to it to do this effectively and appropriately.
If you don't do this, you might as well just let a machine play the music.
BTW. This is a good thread. We really need to focus on our characters as much as we focus on our sleights.
Thank you for posting this, I haven't gotten around to watching the videos, I'm at university at the moment, but I'll be sure to when I can.
I agree and an attempt to help people who can't make the connection about this example and magic.
A classical piece of music is like the stock instructions you get with a rising deck. Just as a musician is supposed to take their song and change and contort it into something that doesn't even resemble the original piece of music a magician is supposed to add their own emotion and personal touches. This is more easily accomplished with the understanding of your character.
In the recent adaptation of Macbeth Directed by Teller and Posner re did the comic relief the "Porter" into something totally different. He was an in character comedian basically. He interacted with the audience in his drunken stupor before returning to the stage where he finally answers the door.
Why do I mention that? Well because it is a great example showing how an actor can interact with an audience in character without a script. I don't know these are just my thoughts on the subject, they may not be all right but it is all good. ^^