(if the subject matter is interesting, the full video is here, I just extracted the juicy Bob bits)

It's kind of mind-blowing.  What has gone wrong such that a guy with a piece of chalk and an eraser can knock the pants off of Keynote.  Even Ken Perlin's cyber-chalk isn't near this level of improvisational fluidity and expressiveness, let alone... omg, is Bob pointing to his diagram with his hands?  Is he pointing to two things at once?  what sorcery is this