This is a really interesting thread, I find animal intelligence to be fascinating.
Redcatcher, I bet they won't have any problem with color differentiation once they figure out what you are asking of them.
I have seen similar videos of clicker training, including ones where chickens complete agility courses.
I haven't had the patience to train my chickens in a systematic way. I have thought about introducing a mirror to their run to see if they would show evidence of recognizing their reflection.
Here's my story:
I had an ornery 2 year old OEG who I hand raised who was upset that he and his hens were relocated to a new aviary. Instinctually, he wanted to go back to his old coop of course, he just kept staring through the wire mesh at his old coop. It was getting dark and I felt bad for him, but I wasn't sure how to help him since we hadn't been on good terms since he became protector of his flock. I wanted him to join his hens who were starting to roost in their new shelter. On a whim, I held up my arm and pointed to it trying to signal that he should fly up and perch. To my amazement he flew up and politely perched. Then I walked over to the shelter and waited, after a minute he flew over to the roof of the shelter where his hens were roosting on the perch.
As a chick he had perched on me, but never on command, so this wasn't something that he was trained to do. Although this story provides nothing that is measurable or repeatable, it suggests a certain sophistication of social cognition. It reminds me of how injured chickens somehow seem to know that I am trying to help them by treating them.