In September, AOL bought Adap.tv. While it might not have seemed a massive deal at the time, in the same month AOL surpassed Google as the company serving the most online video ads in the U.S. AOL ran 3.72 billion video ads to reach 50% of U.S. online video viewers, as opposed to Google’s 3.24 billion and 36% spread. The secret behind the win is the Adap.tv deal. The firm accounted for 84% of the video ads attributed to AOL. Adap.tv’s exchange fills ads for many publishers, including AOL itself. That said, Google continues to dominate in terms of audience size, thanks to the company’s massive reach into YouTube and other corners of the Internet.