http://www.youtube.com/watch?v=Ny7krNFAD1s

This video is an introduction to digital media for geeks. Host Monty Montgomery presents the technical foundations of modern digital media via a half-hour firehose of information. 

The program offers a brief history of digital media, a quick summary of the sampling theorem, and details about low level audio and video characterization and formatting.

The video, via xiph, is free to share under a Creative Commons license.