As usual, Cringely mixes number crunching and analysis, and produces a great paper:
“Twenty million viewers, on average, watch "Desperate Housewives" each week in about 10 million U.S. households. That's 210 megabytes times 10 million downloads, or 2.1 petabytes of data to be downloaded per episode. Fortunately for the download business model, not everyone is trying to watch the show at the same time or in real time, so iTunes, in this example, has some time to do all those downloads. Let's give them three days. The question on the table is what size Internet pipe would it take to transfer 2.1 petabytes in 72 hours? I did the math, and it requires 64 gigabits-per-second, which would require an OC-768 fiber link and two OC-256s to fulfill.”
Part of the solution is in his article, and he mentions some companies trying to address the problem.