So I downloaded it, thinking that 44MB wasn't very much. And, as I suspected, the installer is now downloading 3.7GB of extra content.
Guess what - it'll have to do exactly the same thing again on Julie's machine. So rather than downloading the content once, it's going to download 7.4GB.
I don't know who thought this would be a good idea, but it really wasn't...
I AM WRONG!
It is smarter than it looks. I started the download on Julie's machine half an hour after the download on my machine, it quickly ramped up to 5MB/s (which is significantly faster than my broadband is this week), and slurped it down from my machine via the wonders of P2P.
I take it back, Blizzard coders, you are smarter than you look!
Original post on Dreamwidth - there are comments there.