This is interesting, as airlines won't kick boarded passengers off for other passengers (to my knowledge). What's probably happening here is that pilots or attendants need transportation to their next scheduled assignment, for which the airlines will force boarded people off. At that point the airline's computer runs through the passengers and picks whoever paid the least. In this case the attendant was probably trying to solve an impossible problem that the airline created, but saying retarded things (like "you'll get your kids taken from you") in the age of cell phone videos is super stupid. This particular attendant needs to be re-assigned to a empty return flights, they don't have the social skills to handle the job.