These kids are adorable and a joy to watch. I especially enjoyed the conflicting emotions revealed in their facial expressions.
On my second viewing, I noticed that with the exception of the two boys in the room together (and even then), there were no children of color. Which got me to thinking that this “experiment” and the experiment on which it is based do not just measure a child’s innate abilities to defer gratification. For example, the experiment might also reveal a child’s ability to measure the reliability of promises that adults make.