@MK14, what are you talking about. Get rid of your ad blocker. I have no ad blocker and the youtube video you posted had no video ads in it. Just 3 little pop-up banners at 3 points in the video. Your ad blocker is making youtube give your extraneous ads which isn't even an issue on your linked video for those of us who don't cheat.
As a result of my ad-blocker, I had received no adverts on youtube, for a long time. Maybe the last 12 months. When using Chrome on this computer, with the ad-blocker enabled. Unless I opened an incognito window.
That particular advert, seems to be targeted at me in particular (or rather the marketing group(s) which google have probably assigned to me). My understanding (but I'm GUESSING) is that adverts are targeted at users, rather than necessarily being 100% connected to particular videos. Although particular videos (e.g. EEVblog = Electronics - Electronics related adverts make sense), also probably trigger things at google as well.
There is probably lots of information about it on the internet (online adverts, and how they work), but I've probably never read them, and have little interest in them.
If I use Chrome now, it still tries to show me that advert (so I stop and close it, almost immediately).
So far the Mozilla/Firefox has been ad free. So I will keep at it (use it when I watch youtube), and see if it continues to be ad-free long term.
If I open an incognito window in Chrome (it hides all your cookies and other private stuff), it shows a different 20 second advert (or rather tries to, I stop it after about 2 seconds, lol).
It seems to be a more generic British Gas advert.
Anyway, in time the truth will come out, as regards this Google/Adverts VS ad-blockers etc VS Google Red subscriptions.
I'm surprised it seems to be only me so far. Googling for this issue (raised recently in the last week), ironically mainly brings up this thread
So it could be a problem with my setup (which has weakened the ad-blockers) or something.