To add video information to a Sitemap or mRSS feed you must specify location of the video using one of two tags: video:player_loc or video:content_loc. In case of mRSS feed, equivalent tags are media:player or media:content, respectively. "We need this information to verify a live video on your landing page and to extract metadata and signals from the video bytes for ranking. If one of these tags isn't included we'll not'be able to verify video and your Sitemap/mRSS feed willn't be crawled," explains Google.
Here's some detail about these elements:
Player Location/URL: player (e.g., .swf) URL with corresponding arguments that load and play actual video.
Content Location/URL: actual raw video bytes (e.g., .flv, .avi) containing video. It's strongly recomended that you provide both.
To better ensure that only Googlebot access your content, you can perform areverse DNS lookup.