Which site? (if you can tell it of course)

I cannot, unfortunately. But it is still up & running after the acquisition (2/3 years ago). Basically it lets people search and download YT videos. Very simple, nothing else.

One smart thing he did was to create a new page every time someone downloaded a video, and at some point he was getting hundreds of thousands of daily visitors (I saw the Analytics charts).

interesting but i can't get how generating billions of pages can get him traffic