I just uploaded an abbreviated version of the Midget Derby video that I did for COPS.
This is the only example of this machine known. No one knows who made it. Some speculate that it was Watling. I have seen and inspected this machine in person. I don't think it was made by Watling or any of the major slot manufacturers. I think this machine was a prototype. I would speculate that machine was made in the late 1930s, possibly into the mid 1940's
This machine was part of the Bill Harrah collection which was recently sold and I have been told is going to be auctioned off in the fall of 2014.
http://youtu.be/__7D-hj2UIM
I will be uploading more videos and pictures between now and the fall auction.