Animal-encounter videos are often destined to go viral, like is this one, in which a group of tourists visiting Yellowstone National Park have a scary face-off with a sow and her cubs. It's amusing to watch, mostly because no one was harmed, but it's definitely a strong reminder that all bears—even the relatively docile North American black bear—are wild animals that can be dangerous and deserve a healthy level of respect.
In the video, you can see a number of mistakes that the tourists made. First, they should have remained in their vehicles. Second, they shouldn't have blocked the path of the bears; instead, they should have backed off to the side to let the bears pass. Third, they shouldn't have turned their backs and run. Running can trigger a predator's prey instinct. What's more, you simply can't outrun a black bear: Their top speed is 35 miles per hour, and they can reach it even in tough terrain. Nor can you outclimb one; bears are accomplished climbers.