Kevin,
I found similar devices when we were looking for a motorized tow dolly for our trailer. (We have a very tight parking spot, on the side of the house, dodging trees, shrubs, and garage overhang, slightly uphill.)
Since all the ones we found were a. expensive and b.
sold in the UK, we opted for something else (the EZ Tug).
Very nifty idea, though! Thanks for the video clip.
Sherry