Blocked websites on macOS host but not on Win7 virtual machine
The firewall might be blocking dynamically, and if so, it could decide on a large number of factors that are hard to guess or summarize. 

For example, firewalls can tell what platform you are using, as well aspects of the network configuration.

What you describe could be summarized as: based on the assumption that Windows is blocked less from YouTube than macOS, your computer is not being blocked for its location on the network, but usually because it is running macOS (in this specific environment). If that same network device was running Windows (or more specifically a Windows-based browser), YouTube works, in this specific case.