Google recently recommended that content creators begin using Schema.org markups when tagging the metadata for their videos. This is a joint effort with Bing and Yahoo to help videos become more discoverable through all search engines.
Schema.org’s video markup has a wide variety of tags that website owners can use the describe the videos on their site. If used in conjunction with XML video sitemaps, it would be virtually impossible for Google to miss a video embedded on a page.
A complete list of the tags can be found at Schema.org.

