Although I'm not sure if there is a revenue model behind this game aside from PR for their company, using the internet's landscape for a gaming environment definitely has a quirky upside for click through referrals.
Er. Those aren't "real" websites. I'm afraid you misconstrued a lame ad for something much more.
I'm fairly certain YouTube is a real site, however...
But the game isn't played on a live version of it - it's just a normal backdrop.
There's nothing technically interesting about this advert - it's just a Flash game.
It's an advertising piece. Basically a big banner.