A video sitemap is used to mark up video content to enable and facilitate crawling and indexing of such content by Google. Video Sitemaps are based on the meta markup language XML and structures the information to be linked to the video or videos. If the markup is syntactically correct, the corresponding video content will displayed in the Google video search and as Snippets in the SERPs because Google receives information about this content from the video sitemap once uploaded.
Content recognition using XML, schema or RDFa is a major step towards the semantic web. Users looking for content can more easily find it in most cases if they it is annotated appropriately. This means that metadata is added to the actual content in order to communicate the content type and how this can be meaningfully described to search engines. Google uses different crawlers for different content types. Googlebot video with the user agent Googlebot video/1.0 for videos, for example. Conventional crawlers can sometimes only read content types such as HTML code or text - an important reason why videos should be marked up.
Video sitemaps tell Google that the data contains video material and how the video material can be described. The syntax of the markup language must be observed, otherwise the content cannot be read by Google and stored accordingly in the index. Video sitemaps are a form of structured data that provides search engines with important information about the content of websites through the use of structured information.
To create a video sitemap, you first have to make a decision about its format. The sitemap can be individually uploaded or integrated into an existing sitemap, which lists the other content of the website. If you want to list a large number of videos in the Google video search, it is recommended to use multiple sitemaps and an index file, because according to Google a video site map should not contain more than 50,000 video entries or exceed 50 MB in the compressed version. Please also note the following points:
The video sitemap can be uploaded in the Google Search Console, after it has been created. Google will then check the file for syntactic correctness and include the video and all meta information in its index if the test is passed.
Here is an example of a video sitemap: 
<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9" xmlns:video="http://www.google.com/schemas/sitemap-video/1.0"> <url> <loc>http://www.example.com/videos/some_video_landing_page.html</loc> <video:video> <video:content_loc>http://www.example.com/video123.flv</video:content_loc> <video:player_loc allow_embed="yes">http://www.example.com/videoplayer.swf?video=123</video:player_loc> <video:title>My funny video</video:title> <video:thumbnail_loc>http://www.example.com/thumbs/123.jpg</video:thumbnail_loc> </video:video> </url> <url> <loc>http://www.example.com/videos/some_other_video_landing_page.html</loc> <video:video> <video:content_loc>http://www.example.com/videos/video1.mpg</video:content_loc> <video:description>A really awesome video</video:description> </video:video> </url> </urlset>
The tag urlset describes the namespace, i.e. the rules against which the document is checked. Under the URL tag you can find with loc the location and with video tags information about the content type, the ability to embed (player_loc_embed), the title of the video (title), and the thumbnail image (thumbnail). The second URL entry refers to a new entry of another video. Correct nesting of elements and the closing of each tag pair is important. The basics of XML syntax should be known.
YouTube is a part of Google and is considered the largest video platform with billions of visitors each day. This and the fact that more than 90% of Internet users in Germany use Google search make it clear that significant marketing potential can be achieved through video optimization, provided the video content is somehow interesting, useful, or helpful for users.
In terms of video optimization, a video sitemap should therefore be considered as an integral part of a multichannel strategy because sitemaps ensure the highest level of accessibility and sometimes increase the click rates by displaying snippets. In this way, Google gets not only signals about the specific content type, but also that the website provides various types of media content, in other words content diversity. Videos should be optimized with structured data and along with video advertising and viral marketing can increase its reach with the Google video search.