Both dns here were running on top of IoT devices (BeagleBone & Raspberry Pi) the DHCP from the Internet provider's box override its dns for my internal ones.
Now they use AdGuardHome since pihole v6 and its catastrophic performances.

Doesn't work https://www.reddit.com/r/pihole/comments/9w5swx/i_think_ive_managed_to_block_youtube_ads_with/

TL;DR;

nslookup manifest.googlevideo.com

On the DNS (using dnsmasq here via pi-hole)

vi /etc/hosts

 <IP from nslookup> manifest.googlevideo.com

reboot/relaunch dnsmasq

 https://v.firebog.net/hosts/lists.php?type=all

Log into the Pi-Hole server
Run the following commands in a terminal window

# output current pihole db size
du -h /etc/pihole/pihole-FTL.db
 
# flush pihole logs
pihole flush
 
# stop pihole FTL service
systemctl stop pihole-FTL
 
# delete the FTL database file
rm /etc/pihole/pihole-FTL.db
 
# restart pihole FTL service
systemctl start pihole-FTL
 
# output reduced pihole db size
du -h /etc/pihole/pihole-FTL.db

Reduce Long Term Log Lifespan
By default, Pi-hole keeps long term DNS logs for 365 days.
This lifespan can be changed by altering the MAXDBDAYS variable in /etc/pihole/pihole-FTL.conf

# edit pihole-FTD.conf
vi /etc/pihole/pihole-FTL.conf

Add or edit MAXDBDAYS value in the configuration file as needed

# restart pihole-FTL server
sudo systemctl restart pihole-FTL

just do a small file with one domain per line and import