I guess the person who captioned the video hasn't seen a fully grown grizzly, if they think this one was massive. To me it looks about 2-years old, and likely left it's mom earlier this season. That might explain the relative timidness and curiosity about the dog, as well as it's susceptibility to intimidation. I think the woman did everything correctly given the size of the sub-adult, but maybe not the wisest move to turn and run at the end of the video - that can trigger a chase response.