TED and iTunes U are nice, but if you really want to see how it was done back before relativist nihilism, the University of Chicago’s Leo Strauss Center has started posting audio files of the political philosopher’s courses. See if you can find the esoteric meaning, or just enjoy it for the exoteric meaning.
For a primer on Strauss, Julie Englander’s 2007 cover story Defending Strauss is a good place to start.