I don't own a modern xbox so I had to do a quick search to learn that this is the famous Dolphin emulator for Gamecube and Wii games which can now be run on the Xbox One which supports apps built for Microsoft's Universal Windows Platform.
Pretty cool! Does anyone know if this requires special firmware does it run on any stock xbox one?
Nope, you can install UWPs pretty freely these days with developer mode. The one downside, is you have to reboot your xbox between developer/retail mode in order to use apps from the other mode.
Is there a free method? Step 5 is to register a developer account and:
Individual accounts cost approximately $19 USD, and company accounts cost approximately $99 USD (the exact amounts may vary depending on your country or region). This is a one-time registration fee and no renewal is required.
Pretty cool! Does anyone know if this requires special firmware does it run on any stock xbox one?