Use a DNS service like ControlD - where you can set individual video services to different settings.
You can then redirect all YouTube traffic on your router through Albania so you get no adverts.
You can also set other video services such as Netflix, Amazon, BBC etc to different countries (all independent of each other, and all to completely different countries if you want).
Also has built in ad-blocking settings and other things controlled by DNS routing.
Really easy to use and change settings using their dashboard.
Because it's a DNS service, not software on the router itself, you don't even need custom firmware like Merlin - it also works on Stock ASUS firmware.