This lady is 70 years old, right? She was born in 1937. While she didn't experience the depression she was probably in a family who's father or mother were serving their country during WWII. She was probably used to sacrifice, and had been brought up with good moral structure. I know what motivated her to go after these teenage thugs. She saw something that was wrong, and she knew that she had the power and obligation to stop it! Right or wrong, and I happen to think that when the situation presents itself we don't stop to consider the danger we could put ourself in, she just acted as her heart told her. Considering her upbringing (and I am only assuming), there was only one course she could take.
Once a year, let's look at similar situations and vote on the most selfless act that we see occurring, and award a Judy Brenner award. Great Job Judy!