Actually, it IS "smiling". Unlike cats, dogs have been found to imitate human behavior, facial expressions, and vocalizations. It's a result of their evolving alongside us. The dog in that video is displaying canine greeting signals, but it's thrown in a human one for good measure.
On Cat Expert: The Shocking Truth About 'OMG Cat'
Actually, it IS "smiling". Unlike cats, dogs have been found to imitate human behavior, facial expressions, and vocalizations. It's a result of their evolving alongside us. The dog in that video is displaying canine greeting signals, but it's thrown in a human one for good measure.