Fast forward. A week later I went back to visit. We set up the trailer the way we normally do and tested to see how he was going to respond. The video is from that first test run. Needless to say, the long and positive history of successful trailer loads overrode the negative experience.
This is one of the bonuses of clicker training that I find very compelling. Behavior can be very resilient when trained with positive reinforcement. It is also one of the bonuses of training a behavior with a horse that volunteers effort, is allowed to set training pace, and where the freedom to choose is a part of the training process.
Because this horse learned to load into the trailer using shaping, he was an active participant the whole process. He had at least a hundred repetitions of good experiences with this trailer, which is a lot of why he bounced back so easily when he had a scary incident.
I just had to share this side of the story to an otherwise “cute” video. I knew you folks would appreciate it.