This experiment turns into a pretty emotional one. While some people are unaffected by the discrimination they observe, others are completely offended on behalf of the victim. One man who objects to her treatment can relate because of his own experiences, but other people (two different white women) seem completely offended by the idea that anyone would be treated in such a way.
Consider (though we haven't talked about this year) what is it about some people that makes them step forward on behalf of a stranger? Some people are content to witness something in their surroundings but are somewhat unaffected by it, while others are compelled to act. What is the motivating factor? Could it have anything to do with each person's place in Maslow's Hierarchy of Needs, maybe? The stronger ones who are higher in the chart, closer to self-actualization, may feel more comfortable stepping forward while others, less secure in themselves and their level of needs, stand back? If the basis for Maslow's needs is that people act to remove deficiencies or continually move up in the levels, what's the motivating factor when the person themselves are not in danger? Ie: If you want to move to step three (social needs) and therefore have attained safety / security, would you feel threatened personally if someone near you were in (a type of ) danger like this woman? Or maybe they're at the fourth level (esteem needs) and taking responsibility of their surroundings.
You may notice, as well, the three things necessary in Motivation: 1) Arousal (something triggers your attention), 2) Direction (a goal-oriented movement to act) and 3) Persistence (affecting the intensity and duraction of your action).
Maybe some people are just especially emotional - is it by their hormones (biological), their mental and emotional empathy for others(Cognitive), or maybe they are just weaker and more insecure than others and threatened by things they see (again... cognitive). What do you think?
You could also reflect on the facial expressions, as seen on the woman's face before the video plays. She's very effectively communicating her response.