Sharing media libraries between Apple Macs - d'oh, I'm holding it wrong

 So I've got a Mac Mini on my home network, acting ( in part ) as a media server, using Media Sharing ( enabled via System Preferences -> Sharing ).

This allows me to share my DVD library across my various Apple devices, including iOS, tvOS and ... macOS.

Having confirmed that I can see / play movies etc. from my iPad and from my Apple TV, I wasn't able to see the media from another Mac on the same LAN.

In both cases, the Macs are using the native TV.app - the Mac mini to manage the library and a MacBook Pro to consume the shared media .....

As ever, I was holding it wrong ...

In TV.app, there's a Library tab, but that was only showing my purchased media: -

The thing I'd missed was the twisty / pull-down under Library on the left-hand side of the app: -

That allowed me to choose the Mac Mini ( I could've also chosen my Synology NAS as that's also got the same iTunes / Media Serving capability ).

Once I did that, c'est voila : -

Thanks to this : -

Import media using Home Sharing in the Apple TV app on Mac

for helping me out of my own mess!