A billion seems low for a company with reported annual revenue of $300 million. Or does it? I can't tell anymore, and I don't trust any of the numbers thrown around.
But let's assume they are accurate and that the following comments made in a Business 2.0 article earlier this year are as well.
"...Conru can't sell his business and start over, even though that's exactly what he would have done years ago if he hadn't slipped into the adult world. He can't sell because AFF is far too big for any adult company to afford and far too dirty for any mainstream company to stomach. And because most investment banks don't want to get involved with pictures of people having sex in their own bedrooms--let alone kitchens, living rooms, motel rooms, airplane bathrooms, and Renaissance fairs--he'll likely never get a fair price for going public."
In that case, AFF may have taken the first substantial offer they got and run with it.