See the latter half of the "concept" video above.
Then, as one gets used to the new positions of the keys and the extra options available, transition easily to the faster and more compact Janko.
Thanks to Bogdan Constantinescu for the following videos.My take: this keyboard is very cool indeed - it's intended to start out as a keyboard that can be played by someone used to the "Standard Keyboard" layout, by playing with the notes as a slight angle - who would have thunk it?
A Brief History of the Terpstra Generalized Keyboard
The Terpstra Keyboard Concept
Then, it you really get funky you can remap to Sonome or jammer or go microtonal.