It's interesting that AdBlockPlus is able to block YouTube ads but PiHole is not. When I started using PiHole and disabled ABP, I started seeing ads on YouTube. I know ABP gets lists of sites to block, so it might be possible to pull/import ABP's list into PiHole. Alternately, I'll just disable ABP for all those websites that realize ABP is blocking their ads and leave ABP active for YouTube specifically...