What Would You Do?

This is the second week I've caught the ABC show What Would You Do? A reality-type show that sets up situations with cameras to see what passers by will do.
The latest clip I just watched was of a nanny in a coffee shop being berated by her employer in front of the little girl she's watching. She's called worthless, stupid, blamed for things she didn't do and is physically threatened. They switch up actors (race and appearance) to see if it will affect people's decisions to step in and do something. It's amazing to see what people will and won't do. It definitely made me think and wonder what I would do in that particular situation. For me, that's a tricky one and I'm sad to say that I'm not sure what I would do. It's also hard to analyse what you WOULD do especially if you're NOT put in the situation (which is why they do the show I'm sure).
In another situation a blind woman is purposely given wrong change (told a $1 bill is a $20) in a way that people can see. The cashier also makes snide remarks about her disability. In a situation like that I would like to think I'd definitely say something.
I just really find this show fascinating because they analyse people's behaviours and specifically in certain situations with certain races, actors, and changing up who responds (women, men, older or younger people).
It's made me definitely think twice about my responsibility to strangers - even if it's not "my business". It also made me think that I probably wouldn't respond in a lot of situations (the ones that are "tricky" or "iffy") and that makes me sad and slightly ashamed. I worry what people would think, but chances are that if I'm uncomfortable, other people in the area are also uncomfortable and will likely back me up if I just step up and say something.