We get this call often in the summer. What is happening is that the videographer is shooting in the sunlight with the viewfinder tilted up. When he moves out of the way of the viewfinder, the sunlight focuses through the eyepiece lens and burns the black plastic elbow near the picture tube. It is the same thing you did as a kid when you tried to start a fire with a magnifier and paper. The focused sun-light melts, burns and smokes the elbow. If it smokes enough inside you stand a chance of fogging up the picture tube. A good cleaning can take care of that problem.

Please just beware that this can happen on all video cameras and you should get into the habit of repositioning the camera or viewfinder, or covering it to keep the sun out of its lens.