Several solutions are discussed here, including live cockpit video feed to pax, which has nothing to do with post accident investigation.
I am in favour of video recordings in the cockpit, encrypted in a form so only the authorities can access them, and kept in a secure manner like CVR/FDR. Erasing should not be an option for the crew nor company.
If a am dead anyway, then let the world see how many times I picked my nose, and where I put the bogers, if they so want! As long as investigators can see that I am not reciting the Koran instead of appropriate checklists, or taking of my shoes because I think I am about to die, instead of performing recall items!
Please distinguish between company surveillance and post crash accident investigation!