From the site:
You are watching exclusive LIVE footage from Alaska's Brooks River in Katmai National Park. Every year over a hundred Brown Bears descend on a mile long stretch of Brooks River to feast on the largest Sockeye Salmon run in the world.
ETA: Asked a coworker how long they'd stay there and she was like, "All day." My first thought was, "Don't they have something better to do?"
No, Tamtams, they don't have anything better to do. They are bears.