The industry has been talking about it for months, and now slightly less than a year after Google bought YouTube, the video-sharing site has launched ads.

YouTube says it will use a new ad format that other video sites have begun experimenting with, rather than relying on pre-roll. The new format will display a semitransparent ad on the bottom 20 percent of the screen. The ad will appear 15 seconds into the video and last no more than 10 seconds. If the user clicks on the ad, the video pauses for later viewing.

According to YouTube, which began testing ads in June and July, 75 percent of viewers watched the entire ad.

YouTube will pair the ads only with brand-friendly material, working with more than 50 content partners that include the likes of Ford Models and Warner Music Group Corp. For now, the most user-generated videos, which account for the bulk of YouTube's library, won't have ads.

In the meantime, YouTube-rival Sony, which recently rebranded its online video site, calling it Crackle, has eschewed amateurs altogether, opting to provide brand-friendly content by working with professionals and aspiring professionals only.