Blocking YouTube from home Router

I found it possible to block YouTube from the router, on anything that does not have cellular access.   Anything using cellular connectivity may go around your router, which is outside of the controllable zone.   Logging into the Xfinity router at 10.0.0.1/admin, using your username and pw that you have set up already (if you have not, the default on some of these routers is "admin" and "password" for the username/password.  Under the tab on the left, find parental control, and click 'Managed Sites'.  Make sure it's enabled.  Start adding in the blocked content list.  Mine is pretty long, being that Google uses a CDN that YouTube is on.  It looked something like this when I was done.

*Note

I did not know if CIDR notation (IP Ranges) worked to block all IP ranges, but I did enter them in.  I found many of YouTubes IP addresses at this lifewire site. https://www.lifewire.com/ip-address-of-youtube-818157, and then I found how to turn a range into CIDR format at this link https://account.arin.net/public/cidrCalculator.  I input several of the most common IP addresses afterwards (again, not sure if CIDR notation works for IP range blocking).  

My question to Xfinity was do you know if CIDR notation will work for IP ranges, or what is the best way to implement a block against an entire range of IP addresses?

Also I figured this might help others who are looking to do the same thing, as there were many articles I found without (out of scope) solutions in the forums.