Luddite much? I would imagine that the P2P aspect of the service reduces costs to everyone significantly. And the fact of the matter is likely to be that the vast majority of the end users on the internet use virtually none of their upload capacity. I'm sure that they'd rather trade that capacity for lower costs.

You talk of "setting up a real network", but the costs of the BBC providing video downloads would be outrageous. Assuming that each video file is 250MB and that there might be 10,000 downloads a day, that's well over 2 TB of data. That means you'd have to have an OC-12 just for the video download bandwidth. OC-12 circuits tend to cost in the realm of $250,000 a month. That means that each of those videos would have to cost $25 just to break even on bandwidth costs. If, however, they were using their customers' bandwidth, they might be able to get by with an OC-3. OC-3 circuits cost in the neighborhood of $25,000 a month, which lowers the cost of the videos to just $2.50 in order to cover the bandwidth costs.

Sounds to me like they might be giving you a cut of the profits by reducing the cost of the items you're buying. Of course, no one's forcing you or anyone else to use their service. Feel free to not be able to get your hands on copies of the programs legally.