ToT likes the odd joke or two - highly entertaining videos, and (without listening to the video) it wouldn't surprise me if that's a bit of a prop for the video.

That said - I'm heavily involved in repurposing the fixed pendant on my mill with something more CNC-based/useful, including axis-feeds, DROs, probing etc, and - at least with UCCNC (and the plugin interfaces) - that 3-axis cube control would be pretty straight-forward to implement (particularly if you only wanted one-axis-in-motion). As Paul suggests - there's more required for a controller - like feed rates.