When we search, we use keywords to describe what we want to fid. Search engines use those keywords to match to content. Search engines rely on being able to use text in the content to determine what it is about, and other indicators to determine how relevant that content is. When it comes to web pages, search engines can “read” the text on the page to determine what the page is about, and can measure the links coming in to determine how relevant the page is. When it comes to video, the search engine cannot “watch” or “read” the video, and instead must rely on other text on the page to determine what the video is about. The search engine also needs to look for ways to measure relevance.