I got most of the way through the video.
First, in this case, I do not think any weapon of any caliber would have helped him. They were attacked from 5 feet, and from his tale, it sounds like he would have been SOL unless he had been carrying something at port arms. Not likely when hiking for enjoyment. Another point that this attack brings up is that a pistol might have been more useful. Something he might have been able to access while the bear had him. A rifle would have ended up who knows where. The better choice would have been for both of them to be packing. At least the second shooter might have been able to intervene.
I can tell you from experience with one black bear that might have had me for lunch if I had not been packing a gun while bow hunting is that an encounter will happen very fast, and you will not be expecting it. Unless of course your idea of a hike or a hunt entails carrying a gun at the ready, at all times, with your attention on exactly nothing else but what is immediately up ahead. If I wanted that, I would have joined the Armed Forces. I still like the handgun in Black bear country. Not really in the way, and I think that I can skin leather faster than unslinging or unpacking a long gun.
And of course, I stay the heck out of National Parks. If I want to see a National Park feature, no problem. Just to go hiking, I'll take the National Forest any day.
Craig