I’d recommend downloading from sources that don’t compress a much/badly as YouTube does ;)

You get amazing features like: background play (which is more of an annoyance), remember where i left off (which doesnt work whatsoever, even 5 years after it was first released), download video’s to watch offline (you need to remember to download them first or hope that YouTube’s recommendation algoritm didnt pick videos you’ve already wachted) oh, and you can get a slightly higher bitrate for 1080p. So basically it loses all value.