On Thursday, Google started testing video ads on some pages of search results. And it is developing ad formats with images, interactive maps and other more elaborate features. In the beginning, users will barely notice the change because the videos will not be immediately obvious. Ads with accompanying videos will have a small button with a plus sign. Google has increasingly used the plus icon to indicate that certain information — like a map — can pop up on a search results page. Users that click the plus button on an ad will see a small video player that shows a commercial, movie trailer or other clip.
For now, advertisers will not pay extra to put video in the ads. They enter a price they will pay for a click in Google’s regular text-ad auction. But in the video ads, the advertiser pays when users click to see the video, even if they never click through to the advertiser’s site. This allows Google to expand what it can offer advertisers that are focused on promoting their brands, rather than driving traffic to a Web site. But Ms. Mayer said the company was not changing its idea that ads need to be directly relevant to what users are searching for. As always on Google, ads are shown based on a combination of factors, including the amount bid and how often they are clicked on. The test is scheduled to begin today in a small fraction of Google searches.