The online video sharing site has in the past week quietly begun working with ad networks.

Rich media banner ads from ad networks, including AOL's Advertising.com and Tacoda, have been appearing on YouTube, reports MediaPost. In addition to the usual Google text ads, the site has apparently been displaying banners on some view pages. The relationship with the networks seems to be about a week old.

The agreement comes as YouTube undertakes various attempts to exploit its popularity and work with advertisers, including partnerships with major studios to show movie trailers and a recent 24-hour rich media banner ad campaign for "Pirates of the Caribbean" sequel "Dead Man's Chest."