I just came across a 2005 article by Mark Pesce on "How Battlestar Galactica Killed Broadcast TV." He speculates that downloaded television can embed advertisements in a more efficient way than broadcast television. A very interesting read.
All the more so for it is asserted that Australians are the most prolific downloaders of television in the world. That this is so is not that surprising; they have to endure the longest gaps between broadcast elsewhere and broadcast in Australia. In some cases, the lag is so long that the DVD is already released well before a show is broadcast (e.g., The West Wing and, dare I say it, Battlestar Galactica).
Pesce's second article on "The New Laws of Television" is also good.