I have ad block on my PC but even after checking youtube was set up on it I am still seeing the adverts at the start of every video (Crossfield, Finch et al)If I watch youtube through my pc browser (which has adblock running on it), then the ads don't play.
Sadly, I haven't got round to trying out various blockers on the Telly to see if the same thing happens. I'm not sure if the Tv (or firestick) browsers are clever enough to run decent adblocking software.