This is four minutes near the end of a 20-minute session. At the beginning, Atty got on the trailer with the side door closed and I left to feed the other horses. He got off alone and then got back on alone.
When I got back, I started walking to the truck and back, just touching the truck. Then I began starting the engine and shutting it right back off again. The first two times I did that, he got off on start up. Then he stayed on through four start ups, got off and on again, stayed on through two start ups, got off and on again and stayed on through four more start ups. Then this clip.
After we were done, I put up the butt bar and he still wanted to play, but I convinced him we were done for the day.