This video explains the mechanics of the single most important online business. This is how Google makes ~98% of its $20 billion/year revenues, and probably 100% of its $13 billion/year profit.
Online startups would do well to learn how this works. I'm surprised it hasn't gotten voted up more.
This is great info, but I would have liked it if the video looked at more sides of the equation. Granted, the advertisers have the most complicated corner of the triangle, but figuring out what I earn as an ad seller is equally useful... which also lets us solve for what Google's share is.