Video or audio taping yourself does not raise legal issues, but what you propose to do raises questions of your employer's policies and willingness to tolerate any taping in the workplace. Your employer has a general right to instruct you not to engage in any taping at the worksite, and even a right to terminate you for doing it in the first place in the absence of such an instruction.
What you describe is a very difficult and challenging issue. Your efforts to cause the intervention of higher managers certainly conform to what anyone would have advised you to do. The fact that management has been unresponsive is troubling. There are some circumstances where the employee simply does not have the power or control to cause a sound solution.
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