Thankfully I've never found myself in this situation with a bear (I have with a warthog, but that's another story). Basically a guy was hiking in Katmai National Park in Alaska, seemingly in late summer 2017 when he ran into a mama bear and her two cubs.
There are plenty of people criticising him in the comments section for not getting off the trail (which is what he should have done in this situation). But I think it's pretty awesome that he had the presence of mind to film the encounter (in landscape no less!). Not only is it awesome to watch, I think it provides a good learning experience for the rest of us.
I'm considering writing a post in the future about bear etiquette when on the trail. In the meantime, enjoy the video and feel free to share you bear experiences in the comments below!