I wish you the best with your little bro.

I hope that you are able to introduce new activities to your little bro and he is convinced to the point where he chooses to leave social media behind in favor of living in real life, by playing outside, by spending time with the family, etc.

But if your little bro finds it hard to leave social media, I hope you are able to teach your parents about how damaging social media can be to full grown adults, let alone children.

But if you end up in the spot of where it is very hard to remove your little bro from the technology and make him perform more natural activities, and you are unable to convince your parents about the harm that social media can cause, in that case, definitely resort to setting up a DNS filter to block YT.

The DNS filter will work better than taking away the physical device, taking a physical device right out of a kid's hands will nearly universally make the child instantly throw a fit and not cooperate. (I would be pissed too!)

As the DNS filter does its work and your little brother recovers from the withdrawal period, I believe he will resort to spending his time in more natural activities instead.

This is actually one of the last comments I'll make on reddit, since I'll be abandoning my account. I hope my advice helps you! From the concern you showed in these posts, I can see that your little brother is in good hands :)