Video is more and more common on the Web. For over a year now, Google has been selectively including videos in search results – even if you aren’t specifically searching for video, which is one of the options in the left column of Google’s search screen now.
But how does Google know what videos you have and what they are about? It isn’t as easy as with most content where the text can be read by Google’s robots.
Google has a recommended way of dealing with this. Here’s their short introduction to the subject of video sitemaps.