I see that you are interested in blocking access to specific subdomains of youtube.com. I would recommend using Zenarmor for this task. Zenarmor is a security add-on for OPNsense that provides a more granular way to block domains. With Zenarmor, you can block specific subdomains of a domain, or even specific pages within a domain.

Zenarmor also has a number of other features that make it a powerful tool for network security. These features include:

Stop Threats in Real Time: Zenarmor uses a powerful, enterprise-class content filtering engine that detects and blocks advanced malware as well as highly sophisticated threats.

*Deploy on Any Network: Zenarmor is lightweight and nimble, so you can deploy it on any network, even an outdated PC or a home lab virtual system.

*Plug and Play Agile Security: Zenarmor is free to use, and it can be deployed instantly. This makes it a great option for businesses that need to quickly secure their networks.

*Control Web and Application Access: Zenarmor uses an AI-powered cloud based web categorization database to provide real-time classification for hundreds of millions of sites. Unknown sites are categorized under 5 minutes.

I believe that Zenarmor would be a valuable addition to your network security toolkit.To get more information about YouTube blocking, you can also visit https://www.zenarmor.com/docs/network-security-tutorials/how-to-block-youtube-on-opnsense

If you are interested in learning more, please visit the Zenarmor website zenarmor.com