7) Social Engagment - Likes, Comments, and social shares are the name of the SEO game. If you have a high likes to dislikes ratio then Youtube will favor your video so the goal is to get as many likes as possible and as many comments as possible. I'm not going to go into detail here as I cover this in this "Youtube VIDEO SEO" tutorial so pay close attention to the end of the video.
Google’s aim is to provide the most relevant result for any given query. Their entire business model relies on them being able to do this, consistently, across hundreds of billions of searches. For that reason, they’ve invested heavily into understanding the intent of queries, i.e., the reason a person typed a specific thing into Google in the first place.