uBlock alone seems to do the trick for YouTube.

I think they're talking about in-video ads?

I could be totally wrong, but ublock-origin just keeps certain things that match a pattern from appearing in the html. It can't remove the annoying "in-video" ads, right?

uBlock Origin blocks in-video ads too! Not sure if this has been referenced elsewhere in the comments but their 'element picker' mode is also fantastic and extremely useful in making webpages with huge banners and popups less annoying. Honestly, being on the web without uBlock Origin (and Vimium) just feels like a sub-par experience.