It's very cool, and uses the same principles as lots of other neurorehab electrical devices out there. I used an FES ('Functional Electrical Stimulation') device for a while that has a little accelerometer in it to figure out when I intended to take a step, and then stimulate (via conductive pads placed atop the skin) the correct muscles in the lower leg to lift the ankle up (dorsiflexion). Over time, when the brain correlates X input with Y result, even if Y is very very weak, bruised nerves can recover (in the case of recent brain/spinal injuries) and new nerves can grow. I was advised to have the device on its 'training' setting (where it would periodically activate a 'step') even when lounging on the sofa. Hebb said: "What fires together, wires together"...

My suspicion (tho I'd love to be educated on this) is that the reference patient did not have a truly 'complete' spinal cord injury, but rather one where there were at least some nervecells remaining/bruised. If there was a complete section of nerve wiring missing, I don't see how re-growth could occur (but perhaps there's some stem-cell wizardry that can help with that???). Anyway, it wouldn't matter much; if these devices become small and convenient enough, it's not much burden to wear them forever.