Why do people who don't own dogs insist on doing these studies? If you ever owned a dog, you'd know dogs don't respond to videos and pictures the way we do, because they know they're not living beings. They have no interest in them. If you put their living human behind a glass wall preventing any of their scent to come through, 100% the dog will recognize the human. I could walk home with a friend and my dog would recognize me through the window. I could be driving and my dog would be able to spot me through the window from afar. This is just another horribly flawed study by people who've never owned a dog in their life.