YouTube is trying to make more money by letting advertisers bid for the right to have commercials shown alongside the search results at the Internet's most popular video site.
The concept introduced Wednesday is based on the same formula that has turned Google, YouTube's owner, into one of the world's most profitable companies.
Just as they do at Google, advertisers can now tie their commercials to specific words entered into YouTube's search box. For instance, a contractor might want to bid for the right to show a video ad when people search for home improvement clips.
Google has become more aggressive about mining revenue from YouTube as it tries to realize a return from the $1.76 billion that it paid for the site two years ago.
Because of fears that the online ad market is taking a hit in the economic downturn, Google stock fell below $300 Wednesday for the first time in three years. The shares were down 6.4 percent at $291.57 in afternoon trading.