Interesting.
I bought AC:BH (PC) the other day from Amazon download service - and the game actually had its own mini-downloader file.
Yeah, their game service is acting more like their MP3 download service now.
So, I saved that file, ran it.
Then, it began a DL of the game.
When it was done, it unzipped the whole installer folder [w/ all the installer files in it] to My Desktop - which is obviously what you'd want to back-up to disc, another HDD, or whatever.
I gotta' see if I can force it to DL the installer where I WANT IT TO.
What Amazon used to do - you'd have to tell Amazon to download whatever game [which is asked to you right after purchase, or you can going through your Amazon account in your Game & Software Library section at anytime], then it'd open-up the Amazon Download program.
{If you didn't have Amazon DL program, you'd be given the option to DL it, then install it}
What was nice w/ the Amazon DL'er - you could set in its Settings, where you wanted installer folder/files to be saved to.
Amazon has always had a decent game download service. Very simple and easy to use.