The tube in my magnavox crt television went out last fall, but we now are still able to watch cable and dvd via the aux input. Lately though, we've seen green flashes across the screen, sometimes the entire screen, and other times just a portion. And it is the same from channel to channel.

Could this be something with the TV, or could it be with the dvr distributing the picture?

I think it is something with the TV.