Just like an XML Sitemap which helps your website data getting indexed, this is a discussion about your website's Video's indexing.
If your website has a lot of videos which are on YouTube, you must create a Video Sitemap to submit to Google Webmaster Tools. This will ensure search engines do crawl your all video data thoroughly which otherwise often may not be.
Video Sitemaps has information in text format about your video content which is directly present on your blog or website or hosted with external links such as links from YouTube. Google and other Search Engines normally avoid your video details and crawl other data.
We are simply telling Google about our video details in complete listed format. That's it. Even if it looks simple it may create a lot of difference when it comes to the page ranking and website indexing.
If you wish to learn more about the Video Sitemaps visit Google.com/videositemaps for more details.
How to Create XML Video Sitemaps?
On WordPress blog, there is a Video Sitemap Plug-in (Source: Labnol.org) using which you can easily create the XML file. Install this plug-in and click “generate” button. It will pull all the video content data and create sitemap file on your site's root directory.
You can upload this file to Google Webmaster Tools for your smoother videos indexing. At current Video XML, Sitemaps works for self-hosted WordPress blogs only and not for Blogger, Wordpress.com or other blogs.