I had something working a while ago for YT ad blocking in chromecast; the underlying problem there is that the chromecast is hard-coded to use Google's DNS serv

I had something working a while ago for YT ad blocking in chromecast; the underlying problem there is that the chromecast is hard-coded to use Google's DNS servers (8.8.8.8, etc) instead of your networks. So you need to set up your network to intercept DNS requests to 8.8.8.8 and 8.8.4.4 and instead send these to your own ad-blocked DNS server. My network setup no longer lets me do this, and I don't care enough to make it work. Just pay for YT premium if you don't want ads (to all those people complaining about wanting an option to pay and not be tracked/advertised to/etc - this is a great opporunity to put your money where your mouth is)