YouTube just announced its first advertising initiative, Dow Jones reports. Here's how it works: "YouTube's new ads involve a semitransparent, animated overlay that appears at the bottom of videos during the first 20 seconds of play and then disappears after 10 seconds. Consumers can close the overlay before it goes away or click on it to launch an ad, currently a video of any length or a flash-animation ad that can link to a Web page. The click-to-play ad pauses the video in a kind of voluntary commercial break, and the video resumes when the ad ends."

The idea is turning out to be vastly more effective than the usual "pre-roll" video ads. In test groups, less than 10 percent of viewers closed the overlays, and five to 10 times as many viewers clicked on the overlay ads to view them compared to standard display ads.

Most folks are annoyed with preroll video ads; 70 percent end up closing the window instead of enduring the ad to see the video they selected, according to the article. So this could end up being an acceptable alternative, particularly on cell phones, where a consumer's time is of the essence.

Google's YouTube To Sell 'Overlay' Ads On Select Videos [Dow Jones via CNN Money]