You may have noticed this and many ad-blockers started not working anymore on Youtube. That's because the site now actively blocks content for those add-ons. While devs still working on it (it usually takes some time), a provisory solution is this:

- If you use a browser with developter tools, turn on responsive design mode.
- Select an iPad or a valid tablet user agent. Be sure that the page reload after you change the UA.
- You can now enjoy the video ad-free. If it didn't work, check if the URL has "app=desktop". Delete it and change the www. to m. on the address site.