Based just on this summary of facts, it is difficult to see any viable cause of action against anyone here. The subject matter of what was reported to the area manager does not apparently obligate the employer to conduct an investigation. The co-worker's statements do not appear defamatory on these facts, and there does not seem to be an issue of reasonable expectation of privacy that would make the videotape unlawful. So, it is not clear to me what legal claim may be contemplated, nor what claim may be sound, if any.
Of course, an in-depth consultation with an attorney may expand the facts to a different conclusion.
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I don't think you have any claims against the co-worker over what you describe.
As an employee, you have very few rights to privacy in the workplace.
Obviously the area manager knows about this, but you can still report the employee to HR for harassing you and see if they do anything about it.