Many employers do not consider their employees as part of their organization. They simply pretend them to be as a mere work force that is being paid to finish up a specified task as quickly and as efficiently as possible. You are not supposed to poke your nose into anything irrelevant to your taste because your employer does not want you to unnecessarily and unwontedly get too involved in the business.
This is the footage of a manager who is taking a good one on one class of an employee who supposedly said something regarding the food being cooked and served in their restaurant. I mean I don’t know why the culprit themselves were filming the footage and uploaded to justify themselves but they are the ones who are actually wrong. Yes, he is an employee, he might be working inside the kitchen and hence knows what all is going on in the background. Why did you stop him to publish or post anything regarding the incident if they were not that afraid? The manager fired the employee that very instant without any certain reason except for him expressing his views regarding the management.