And you'll never guess what happened next.
The polar bear came back and ate another dog.
Apparently the dogs are chained up outside. Just tied there for the pickings. This story is all kinds of weird. Brian Ladoon runs the 5 Mile Dog Sanctuary in Churchill (Manitoba, I think) and he feeds the polar bears so that they won't eat his dogs but neglected feeding them the very same day the footage was taken. And that right there is illegal.
And the consequences for the polar bears are now going to be extremely dire, so say the article at Science Alert.
The article goes into further detail about how this odd "feeding of the polar bears" situation developed.