I really do not see what the dilemma is all about. The cockpit of any commercial airline is nothing more than a place of work for the employee. Any other business has the right to have security cameras in the office therefore why should the cockpit be any different. Unfortunately this is just one more example of "if you have nothing to hide then what is the problem" mentality gone awry, in my honest opinion.
http://www.wired.com/2014/07/malaysia-370-cockpit-camera/