Ah, I see.
That intention isn't quite clear from your topic's current wording. 
You may want to adjust your title accordingly, to attract the right group of users to share their experience.
I'm not aware of any blocklist that would block Youtube in its entirety. Also note that blocklists are maintained by their respective list curators, independently from Pi-hole.
To find out about involved domains yourself, you'd have to watch Pi-hole's Query Log for domains im much the same way you'd hunt for ads: