You cannot run advertisements on pages that play our video content unless there is a significant amount of other important content on the page, meaning that users come to the page to access other content besides the video. In that limited case, you can run ads as long as those ads are targeted to the other content on the page and not to the video or video metadata. For example, if your page displays a video with a news article, blog entry or user profile information, then you can display ads on the page as long as the ads are targeted to the article, blog entry or user profile data.
If you are using AdSense for Content to automatically target ads to your page, use the section targeting feature to exclude the portion of the page that contains the video and its metadata.
Note: If the only reason people go to a page is to watch a video, you should not run ads on that page. If you don't know whether you can display ads on a page, consider whether you would still be able to sell the ad inventory if you removed the video and all references to the video from the page. If so, then you can probably display ads on the page.