I would fire that employee regardless of what transpired before, and I would not hire him in another customer service job if I saw this video before his interview. My primary concern as management would be the safety of the other customers and the spectacle (such as this video) that could be made to make my business look bad. If the customer was a major problem I would deal with them as manager or have the police come, and have the employee taken aside to another room where he can cool off. People in customer service industry need to learn to be professional and calm even in the face of whatever this customer was doing. It is not unusual for people in fast food outlets to have to deal with drunk and rude customers. Being able to diffuse, rather than escalate, the situation is part of the job.