If I'm not mistaken, they count first page uniques, and they define a unique as a unique IP address, and they reset every 24 hours.
So if you have a lot of AOL traffic it may not show that many clicks, but they're not paying per click anyways.
They pay on trial sign ups, even on the free 24 hour trial signups. (They have a recurring program too if you want that)
I don't know about the celeb site, never promoted celebs, but the tour looks pretty sweet
