They stop short of attacking the bear, which would have probably been a foolhardy course of action for them to take. Instead, they circle him, nipping at him but staying just out of his reach. Every time it looks like the bear is about to get one of them, they elude him. They don't get any hits on him, either. But they're not trying to, either. They're trying to get him out of their way.
And they do. They give chase until the bear reaches the treeline, and the bear, probably dizzy from trying to see all of the circling wolves at once, decides to give it up. The wolves can now safely pass through the flat field without harassment from angry, pre-hibernation grizzlies.
Say what you want about wolves, they're darn clever critters.
See the whole video below.