A rather interesting find, really. I was there on June 19 (the day before this video was posted) and both tractors were there, but did not tip. THIS video, however, has a regular sized non-tipping tractor. But then next to it, it appears to be a MJJ sized tractor replacing the other tractor.
Anyone know anything of this? It's around the 2:45 mark.
Radiator Springs Racers (On-Ride Night) Disney California Adventure - YouTube