This is less about "customer demand" and more about having to meet minimum video length for mid-clip monetization slots. Strictly an artifact of how YouTube works.

I didn't know, I pay the Premium to hide that stuff. Regardless, given the effort and lengths they went to, I'm happy to see them do so in a manner that funds their ability to do more.

YouTube know what they are doing… irritate the hell out of you until you buy Premium.

I once had YouTube on in the background and an advert which was an hour long popped up - but I was focused on something else and away from the screen and the tv remote.

The advert? A video of someone pointing a camera outside of a window during the night and onto a dark street (no sounds other than rustling from the person holding the camera). An hour long of it.

Skip.

It was soon after this I paid up.

You ... rewarded this behavior instead of installing ublock origin and never seeing another YouTube ad?

I’ve seen some doing 10 second previews of action parts and then proceed to setup and education. Too bad platforms encourage them to make you watch a couple of minutes of things that you may not be interested in at the time.