Thanks! This made absolutely no sense until the video

I still don't understand it after watching the video. Is the video recorded through a VR headset?

It's a recording of the phone screen running their app. The input of the app is the phone's camera, which they have pointed at their hands holding their Switch. The output of the app is the input plus the game overlaid on top of the Switch.

But is the idea that this would eventually run on a VR headset?

Oh hey! Nitter is working again! Good to know