A little over 2-years ago I was asked by a filmmaker at Burning Man to shoot some footage for a film she was making. Based on the "Gift Economy" concept at Burning Man I agreed to film several scenes for her without compensation. This of course did not preclude a credit in her film as one of the "Directors of Photography". The film has been released and the credits for my work are missing. I am wondering how I need to approach this error to get it rectified and what are the potential solutions given that many DVD's have already been produced without the credit information?