Hello,
I would like to know the best configuration I can do for a Samsung TV on my OpenWRT router.
What is your firewall configuration (open ports) ?
Are you able to block adds and how ? Are you able to block YouTube Adds ?
Feel free to share any other configuration that can improve the use of a Samsung TV ! 
Thank you !
So not trusting the Samsung firmware any further than I can throw it, I essentially operate the 43" Samsung as monitor/speaker combo and drive content either via a full fledged computer or via an appleTV (which has similar trust challenges as the Samsung firmware 
).
I can only see opening your firewall so [malicious] people overseas can control your TV.*
*If you're under the impression that opening ports makes packets "go to the TV faster" or without "restrictions" - the firewall is intelligent enough already to Establish/Relate traffic. Firewalls have done that for about 15+ years now. No need to open ports on a default OpenWrt firewall setup since the TV on the allowed LAN will initiate the request.
FYI, if successful, you might also block a portion of the Google CDN not ad-related (ads in some cases seem to be on servers with other content), YMMV.
No, I don't want to open ports but the other way, I want to block not needed ports for the TV.
For now, I've let only 80 & 443 open to the internet from the TV without issues to report. No ports are allowed from WAN.
Gotcha!
Well, likely 443 and 80 is how a lot is done. From your description - you already blocked all except 80 & 443/tcp.
That's the default anyway, so that's cool.
Adblock has a smarttv blocklist, which actually caused issues with my Samsung TV, so I no longer use that block list. But it has been well over a year since I tried it so you may want to start there to see if it does what you need from an adblock perspective.
IMO, of much more importance with IoT devices like smart TVs is to put them on their own VLAN so that they cannot connect to your home computers or cell phones. Once segregated from my home LAN, I don't care what ports they use to initiate outbound connections to the internet. You limit outbound to 80 & 443. One outbound port is no different than 10 outbound ports. If the TV is phoning home, why do you care which port it uses? Just trying to figure out your use case.
the smart tv block lists are good for privacy/adblocking.
Also YouTube advert blocking really require browser blocking.
Use either simple Adblock or AGH for the list blocking.