From the video description:
"This puppy was lost in front of my house and I went to feed him. I noticed he had a disorder and thought his paws wanted to eat his food. I sent the video to a local Facebook page in my city and it went viral. Thanks to that, the owner of the lost dog found him and went to get him. "
Some veterinarians say this is a neurological disorder.
The dog really starts to attack around the 1:20 minute mark.