As a general rule of thumb, don't necessarily believe everything you read and see on the Internet. This is the case with a video from Youtube user Kelly Murphy, which shows her being chased by a bear down a mountain. The chances of you cruising down a run, while a massive grizzly chases you without noticing, especially during the heart of winter, seems unlikely.
If I had to weigh in with my opinion, I would say this video is more fake than Donald Trump's tan. Nice try Internet, better luck next time.