This is a long shot... But if you use Linkedin that could account for some of the videos. They recently added an autoplay feature for their videos on the home p

This is a long shot... But if you use Linkedin that could account for some of the videos. They recently added an autoplay feature for their videos on the home page that is very tedious to shut off. If you're logged into youtube on the same device it will play the videos and show up on your played videos on Youtube.