The dog mad at his own foot makes me wonder if he had everything working correctly upstairs.
When I was a kid we had a Dachshund who would bear it's teeth like that one in the video if you went near her food. I don't know if I'd trust that leg chasing dog with what sounds like a young child in the clip. It's definitely got mental issues and could badly injure a child I reckon. We had to have the Dachshund put down in the end after she took a chunk out of my Nan's leg.