Let's take for example. A great show, but if you want to buy all seven seasons from iTunes it'll cost about US$280. Want to buy it on DVD, which gets you not only subtitles, but extra features like commentaries, featurettes, outtakes, et cetera? Amazon will sell it to you for $210. Sure, there's the convenience factor of instant gratification, but is it worth the extra $70?

Throw in the fact that I'm already paying for cable every month. I can't easily do away with that cost, as the same company provides our house's Internet tubes. So paying to download those shows means, for me, paying .

Then there's the issue of permanence. Sure, might be good enough that I want to own the whole series from pilot episode to series finale. At an average of 10GB per season, I'm looking at 70GB--that's not a ton by today's standards of terabyte drives, but it's still just show. Turn that into four or five shows, and it starts to add up.

And that's definition. Season 3 of in high-definition will take up 32GB on its own, at a cost of $50 (there, at least, Amazon is selling it for around the same price), but you still don't get the extra features.

But the biggest problem that iTunes has had to overcome in the television market is consumer inertia. People are just getting used to watching television at the place and time of their choosing, whether it be via iTunes, DVR, or online streaming. When Apple introduced television shows on iTunes, Steve Jobs said: "We're doing for video what we've done for music--we're making it easy and affordable to purchase and download, play on your computer, and take with you on your iPod." But people aren't used to shelling out per episode for something that they used to be able to get for free (or, at least, as free).