Where?!
First of all, can I just say: ITV IS RUBBISH!!
You'd think they'd learn a thing or two from BBC and Channel 4, wouldn't you?
Anyway, from what I've found, you have to actually start playing the programme you want to download. If you hover your mouse over the top right corner of the viewing box, you'll see a 'Download' popup. But don't click download until after the advert finishes, or you'll just wind up downloading 30 seconds of advert.
Here's my problem, though. I've clicked download, and it's telling me it's downloading. Fine. But it's only downloading 15 minutes. I'm up to 6 of 15 minutes. Where's the rest of the programme??
******
OK. Great. Now it says 'Unable to download.'
You know what, ITV? I give up.