Completion rate: Completion rate is the number of people who completed your video divided by the number of people who played it. Completion rate, and other engagement metrics, are a great way to gauge a viewer's reaction to your video. Do you have a low completion rate? Are people all dropping off at a certain point? This might be a sign that your video content is not resonating with your target audience.
But Google has championed machine learning as its future and seems 100 percent focused on growing this segment of the algorithm. Going forward, SEO practitioners will need to be proactive and invest in analyzing data and understanding search behavior across a variety of search and social platforms. This way they can develop the type of content that will motivate and influence user/search behavior which will in turn influence rankings and traffic.