Multi-threading should just really be called "intelligent scheduling." It's making more efficient use of a CPU core by scheduling multiple different lines of code to run on a core at the same time. Some bits of code take longer to run then others and don't make full use of the CPU during the time they run, so the CPU will schedule another thread/code snippet to run in that gap of downtime.
I'm certain someone will correct me and add clarity to this explanation, of course.
The problem with this is that Alphabet already collects and sells your usage data. When you use any of Alphabet's "free services" you are the product. What they're doing is double dipping. Not only that, but they're getting very intrusive with the ads.
I can remember a time not long ago when the only ads on the platform were in the form of banner ads placed in the bottom of the video and off to the side next to recommended. There were no ads in the player. If they went back to that, I would not mind disabling my ad blocker.