Algorithm, Search & Distribution
Search ranking
Also called: video ranking, rank in search
YouTube's search ranking weighs how well a video matches the query and how viewers who searched that query behaved after clicking. Relevance is estimated partly from the title, the description and the content itself. The same video can sit at the top for one phrasing and nowhere for a close variant, because the calculation runs per query.
Two habits cost people traffic. Treating a rank as permanent when it moves constantly, and chasing a high-volume head term that established channels already answer, when a narrower query with clear intent is easier to win and brings viewers who wanted exactly that video.