That guy IS a badass. With one arm down the bear's throat, he must have wrapped the other arm around its two front legs, to keep it from slicing him with its 5 inch claws. The bear probably stood up to try get the guy off him, and since grizzlies are about 8 feet tall he must have wrapped his legs around its waist to get high enough to bite its neck. Then he had to get his mouth through all that fur, and around the wide circumference of its neck, and through all that muscle to bite its jugular. I'll bet he had to bite down for at least 30 seconds, so it's a good thing he was so confident about where the vein was -- all that study of bear anatomy sure came in handy. Even after it passed out, the stick he used to kill it must have weighed over a hundred pounds. He probably pulled a small tree out of the ground to do it.
This story inspires me to have my own plaque made, to commemorate that time I scared off a herd of elephants with my dick.