Millions have seen the videos. More than 56,000 migrants arrested and detained since February. >> Yeah, that's 48.>> I'm a doctor. >> I'm a doctor. >> Nearly half of them without criminal convictions or pending criminal charges.>> Hi. Are you a federal agent. >> Here in the town of Waltham, just outside of Boston, groups like these say they're fighting back.>> People often use the word resistance. Is this what the resistance looks like. >> Hell yeah.>> Founded in February, Ferasa's volunteers go on near dai ...