Hello everyone
I am a total n00b to all this, but I followed this tutorial on YouTube, and I now have PiHole setup!
How many "Clients" should I be seeing on PiHole's Dashboard? I feel like my setup is wrong because I still see a lot of ads on YouTube! 
I have the Chromecast with Google TV connected to my TV, and on the YouTube app on there, I see get a lot of ads.
What have I missed?
For some reason, I can't edit my own post, but here is the tutorial I followed.
You dashboard shows that your Pi-hole is used by 5 clients which sounds reasonable for a home network.
With Pi-hole you can't block ads on Youtube without blocking it entirely. YT serves ads from the same domains as video content. There is no way on a DNS level to block the ads. You need a browser plugin to filter the ads based on the URL. On clients where you can't install browser plugins, you can only
Damn you YouTube! Thanks yubiuser, that would be why. 
