Isn't the TWiT network a bit of a special case with Leo Laporte trying to monetize and self produce the same niche of programming he was doing with the Screen Savers back on ZDTV? There isn't much of a choice when the point of the screen casts are that they should be your job. Also it helps that we're conditioned to see adverts everywhere.
There was a time when TWiT was funded exclusively by donations, making a point of not taking ads in order to stay independent. At some point I guess the temptation become too big.
