YouTube ranking algorithm and the Google ranking algorithm.
There is a massive difference between ranking videos on google.com and ranking videos inside of youtube.com). Even though these companies are both owned by Google the algorithms for ranking and also the factors for ranking inside of these platforms are completely different.
YouTube is primarily looking at four separate things number one is they are looking at your brand of 40 or Channel Authority along with their looking at your overall keyword Authority how many videos have you made on this topic or uniformity for this topic. Along with looking at Channel and keyword Authority YouTube is looking at your click-through-rate on the videos that you produce. Along with looking at the overall watch time for your videos.
Google.com on the other hand has its very own ranking algorithms. Even though they have a video section they also have a organic listing section that shows videos. Watch time and click through rate on YouTube has some effect on the rankings within google.com however it's not as large of a factor as people sharing the videos, the amount of in beds for the videos, along with backlinks going to these videos.