We went there in 2010 and did a little bit of volunteer work with a group focusing on mountain gorilla preservation. We did the one-day hike through Bwindi thing and had what we considered an amazing encounter with a gorilla group, but not like this. I'm just impressed at the relatively calm dominance of the silverback in this video. The silverback we saw was far less tolerant, partway bluff-charging our guides when they walked in a direction that he wanted to go (they bluff-waved their machetes around in response, and everybody settled down). You're not allowed to approach the baby gorillas but they can approach you. We had one that came within ten feet of us, and that was pretty amazing to us.
The silverback in this video is calm but not completely, like at minute 2:50 when he pulls an infant away that was intensely scrutinizing the tourist's face. One interesting speculation is that the silverback may have thought that staring into the man's face would be somewhat threatening, as it would've been to the silverback, but it would be hard to reason all the way through that without using a theory of mind. And the silverback's quick glance at the man as he left was interesting - somewhat cautious, a bit threatening, and I suspect maybe just as curious as the females and juveniles but constrained by social norms from showing it as openly. Or maybe I'm just anthropomorphizing, but it all seems plausible.
Only 700 of these guys in the wild, split into two geographically-separated groups. As we see from the population structure of one male and a number of females, the effective breeding population is far smaller. These gorillas haven't been bred in captivity.
Here's hoping this video helps raise awareness and maybe some money to keep the species alive.