It's hard to explain, but basically (based on the video): You can pay to use any video on YouTube as an ad regardless of whether you actually own it. You can

It's hard to explain, but basically (based on the video): You can pay to use any video on YouTube as an ad regardless of whether you actually own it. You can also set the title on these ads to anything you like. So people can basically tank your videos/channel by advertising your work under misleading titles/descriptions, since the algorithm tries to recommend videos with decent view times (and misleading titles give you a really bad bounce rate). Kinda like negative SEO for YouTube.