You won’t in any way be impressed by this, but if you really want the new Windows 11 Media Player app, here’s how to do so.
First, and most obviously, you need to be running Windows 11. I assume you’re on the stable/release version, as I am, because you can get the new Media Player app now via the Windows Insider Program’s Dev and Beta channels already.
Second, check out the original source of this tip, which is ghacks. It’s reasonably straightforward.
As hinted at by the URL of the Store listing for this app, it is exactly what I thought it was, an updated version of the Groove Music app that now supports video playback as well. Amazingly, it’s even less full-featured, which is saying something.