"video cameras in use"
"premises under video observation"
etc.
Taking a job that requires you to keep some information confidential concedes your right to free speech.
Heck any time you agree to a terms of service you are probably conceding certain rights to the company you are dealing with. "(Company name) retains all ownership of copyright for any entries to our contest"
your right use privacy does not trump their right to security if you want to use whatever service they are providing.
Why are you equating private institutions to government?
The Constitution is there to regulate government, not private institutions.