You may need to speak with a workers' comp attorney as well as an employment attorney. If we were to assume that there is video of you, showing something, from a workers' comp standpoint there is a question of "so what?" Is there a relationship between your injury and whatever it is that's on the video? Try the link above for Find a Lawyer in your area.
I don't think that they would bluff with something like that, and only you know whether you are guilty. They can absolutely use the video, so I would act accordingly.
I represent Employers, but I can recommend Worker Attorneys in So Cal if you ask.
Not sure about what "tampering with the equipment from a camera" has to do about a work injury. If you are hurt in the course of employment they are responsible for medical treatment. They may be responsible for indemnity (wage) benefits if the injury disables you. If, however, you are terminated "for cause" this may well effect your entitlement to the indemnify benefits but not the medical coverage. The camera thing is a bit confusing. If the tampering was wrong and you are terminated as a result it can, again, create issues with receiving your wage benefit but does not eliminate your right to medical coverage. More really needs to be understood about this camera thing.