I am trying to find videos of the Vetrix Global ES-3 in action, but all I can find so far is a You Tube vid full of snapshots.
I, too, could find no actual videos.
I did raise an eyebrow at this (from your link):
I think they mean “zero-radius turning”. Properly speaking, zero-degree turning means the thing doesn’t turn.
Just make sure the slowest one (the horse) is in the middle to steady the others. 
A friend of mine says they used one in the third MIB movie near the beginning-I’ll check it out when I get the chance.
It might actually mean zero-degree turning - if the handlebars don’t have to be turned and it will go around a corner by slowing the inside wheel.