I'm assuming the 600% claimed is a ratio of 1:6. I don't think it was meant to be the gear range because the minimum is zero ratio and you can't get a range by dividing by zero.

But if you can always dial your ratio to zero, does that mean you have an infinite number of possible gear range from zero to whatever maximum you want? Because whether you choose something like a 44t chain ring or something ridiculously high like 72t, with an 11T rear cog, you can always dial it down to zero.

I am assuming though at the very low gear ratios below something like 0.5 that perhaps the amount of movement in the selector arm is so incrementally small that it's impossible to set and effectively drops to ratio of zero. Let's assume the effective ratio starts at 1.0.

I have 12-34t and 24/44 on my Dahon, so I've got a gear ratio of 0.706 to 3.667. I really only ever need at most 4.2. since the hub would have a max ratio of 6, I would need a rear cog and chain ring combination to reduce that to 70%. So if I have a maximum 50 tooth rear cog then I would need a 35t chainring. And I would have an effective ratio of 0.70 to 4.2 which would give me the 600% range.

A 16 inch wheel would need an equal rear cog and front chainring for 1:1. 33t/33t.

The video showed a remote that operated a battery powered motor to move the selector arm that controls the variable ratio. And also claimed that it can be made automatic, I guess through a power meter, but I wonder if there's a manual operation such as with a pull cable.