Most bears don't want trouble and will leave the area as soon as they detect you. However, that's not always the case, and there's always a chance you'll have to deal with a bear charge when you're in bear country.
Hunters are particularly vulnerable to a bear charge because they do things that make them hard for bears to detect, like moving quietly through the woods with the wind in their face. It's not unusual for curious bears or bears that get startled to act aggressive towards hunters.
From the looks of things, the bruin in the video below got a little too curious and was trying to determine if this hunter would make a good meal. How would you have reacted in this situation?
As you can see, the hunter really didn't want to shoot that bear. Maybe he didn't have a bear tag. Maybe he was deer hunting and just didn't want to deal with a dead bear.
Either way, he did the right thing by yelling and making himself look as big and unappetizing as possible. If the bear didn't get the message, he was prepared to shoot.
Keep this in mind if you're ever on the wrong end of a bear charge and try to deescalate the situation before deploying bear spray or your bear-defense gun.