Google: Video must be main content to appear as thumbnail

Video thumbnails will only be shown in Google’s search results when a video is the main content of a page, Google announced today. “Today, we’re making a change so that video thumbnails only appear next to Google search results when the video is the main content of a page. So how does Google determine when a video is “main content”? Annotations will appear in the video indexing report and video enhancement report, Google said. Google will still show a video thumbnail to the left of a search listing when Google determines a video is the main content of a page.