Just came across some very interesting info about some new Cloudflare DNS features that were introduced in April.
In addition to their standard 18.104.22.168 DNS service they now also have:
Malware Blocking Only
Primary DNS: 22.214.171.124
Secondary DNS: 126.96.36.199
Malware and Adult Content
Primary DNS: 188.8.131.52
Secondary DNS: 184.108.40.206
They are also planning on introducing category whitelists/blacklists that can kick in at nominated times of the day. No details about how they plan on implementing it though.
If you want to test how those DNS servers resolve specific domain names without changing your setting you can go this tool and enter the domain name and the DNS server you want to test. The result for a blocked domain would be something like this:
"A" DNS records for testdomain.com, [DNS server 220.127.116.11]:
testdomain.com. 60 IN A 0.0.0.0
Where an IP address of 0.0.0.0 indicates that the domain is being blocked.
Would probably render it not really useful if YouTube videos are excessively blocked.
It won't be able to distinguish between videos because it is domain based and not URL based filtering.