While a lot of this stuff is clearly composed, they do a great job of making it feel like an "in-the-moment" jam session. Not to say that it isn't, however, as there's a good amount of improvisation going on as well. Either way, they're strong on both fronts.This also happens to be the modulating version where they just keep ascending through keys. Not only is it entertaining, but they manage to hold on to (and maybe even build upon) the level of energy that they have in the original performance.
Got any favorite jam sessions?