Do Dogs Really Know Right from Wrong? [VIDEO]

Can a dog really know what is right and what is wrong? For those of us with dogs, when our four-legged friend does something wrong, there is always that sad-puppy-dog look, right? And because our dogs give us that look, is that enough proof to show they know they did something wrong? For us dog owners, we usually think so. However, as you'll see in the video below, according to at least one researcher, it could just be dogs know how to react to their owners. 

Decide for yourself. Here's the video from PBS. What do you think?