Go to Cyclocosm. The proprietor, Cosmo, has started a series of short (< 5 minute) video recaps that illustrate and analyze what happened in a given race.  He does such a great job that I don’t think you really need to know much more than the basics (i.e., cycling is a team sport, a team usually has a leader that it supports in order to ensure he crosses the line first, and it’s always easier to move faster in a group than when you’re alone.). Here’s the video Cosmo put together for yesterday’s Paris-Roubaix race:
How the Race Was Won – 2009 Paris-Roubaix Video Analysis from Cosmo Catalano on Vimeo.
If you liked that, you can find a number of videos covering this season’s races at Cyclocosm.