This is an experimental feature, provided by Diversion. This IS the thread for it. I am not going elsewhere with that discussion.
As it is an experimental feature, documentation is sparse.
But here's how it works: Whenever the grabbing feature (opt/share/diversion/file/yt-blocking.div) finds a new *.googlevideo.com in the Dnsmasq log file, it adds it to opt/share/diversion/list/yt_blacklist. That file is loaded into Dnsmasq and next time one of these domains is requested, it gets diverted to the forced IP address(es) which can be viewed in b 8.
Forcing all *.googlevideo.com domains to the same and only forced IP address presumably effects in fewer or no video ads shown.
The forced IP changes at a certain interval, the change is logged to the router's Syslog, along with any new domain names it grabbed.
This short explanation will have to do for now.