Under my jurisdiction, I have the lawful authority to detain people for up to six hours while waiting for the police. As long as I've seen the crime being committed with my own eyes - no sweat.
BTW, that mp3 player cost more than a hundred dollars.
More than $100 is usually a felony. That changes things as well.
I was not arguing with you, only stating that someone who knows what they can do and are allowed to do, should execute such actions. Otherwise they might end up in court for legal reasons.