Video SEO (vSEO) is the process of improving the ranking or visibility of a video in video search engines or search engines in general, allowing it to show up, preferably, on the first page of results. This process involves creating video metadata that is relevant to what people are searching for as well as building video content that generates traffic for a specific website.
Techopedia explains Video SEO (vSEO)
Video SEO is a component of SEO that is used to leverage the information delivery and attention retention capabilities of videos to drive traffic to a website, promote conversions and retain audiences. Studies show that an average user stays and browses a website for an average of 4 seconds, but stays and watches a video for an average of 2.7 minutes. This shows the power of videos in terms of retaining an audience. Video SEO is used to make specific videos show up in the first page of a Google search result, for example, in the same way that regular SEO promotes the actual website in search results in relation to the search term.
Since actual video data cannot usually be seen by Web crawlers, which are usually built to find text, the conventional SEO process used for video SEO is to use tags and metadata to lead the crawlers to the video. However, some crawlers specifically made for videos can look at video data to know the content to some extent, but this is not reliable and not applicable to most types of videos. To date, the most reliable way to promote videos in searches is for the website to have a video sitemap, which is a basically a gallery of videos being hosted on the site itself. This is because Google usually only accords rich snippets to sites with large video catalogs such as YouTube, Daily Motion and Vimeo, so having a video sitemap tells the search engine that the website also has a large video catalog.