That's not a demo, that's a vision.

Better put. As an aside: the headset and gun exists (https://www.wareable.com/vr/starvr-headset-review). The location soon exists with enterspace vr: https://www.enterspacevr.com

Any recommendation on how a common mortal could invest in ML?

invest in their known publicly-traded investors (google. others?). figure out who manufactures the more expensive pieces of silicon (or optics?) in the device, invest in them.

real paintball is unbeatable -;) nature always wins