*"The point of such a presentation is to take a piece of code that the presenter...

"The point of such a presentation is to take a piece of code that the presenter has understood deeply and for them to help the audience understand the core ideas..."

I do get lots of value out of that. My favorite example is Beazley's GIL talk: http://www.youtube.com/watch?v=Obt-vMVdM8s