Yahoo on Wednesday introduced two online video advertising formats, and said it would also offer overlay ads through its recent acquisition of Maven Networks.

The two new formats include one in which an ad that appears either before or after a video contains a cue for the viewer to mouse-over the video window. Doing so displays a message in a semi-transparent overlay on the video ad. The message prompts the viewer to click through to the advertiser's site for more information.

Along with the above "clickable" ad, Yahoo introduced a three-second splash ad that appears when a video is launched, but then becomes a banner ad above the video window. When clicked, the banner pauses the playing video and launches an interactive ad.

Yahoo has made the new ad formats available in the United States on all videos across the portal's network. Companies that have used the formats include Adobe, Esurance, HBO, and Sharp.

Maven's overlay ad is an interactive or Flash media ad that runs inside the video player, but on top of the selected programming. The ads can be displayed as splash screens, as well as in the middle of the video or as a live-feed insertion. "These formats increase the available inventory and choices available to publishers," Yahoo said.

Yahoo acquired Maven Networks last month for $160 million. The company didn't sell ads, but was heavily involved in testing new ad formats that go beyond the typical clip that runs before the video. Maven delivered content with ads inserted to more than 30 media companies, including Fox News, Gannett, The Financial Times, Hearst, E.W. Scripps, and CBS Sports.

Yahoo over the years has seen its overall share of the online advertising market shrink, as Google became the dominant player, primarily through its success with text ads tied to search results. Yahoo's drop in stock price as a result of its failure to grab a bigger share of the ad market has led to a takeover attempt by Microsoft, which is ongoing.