This 2015 video is called Polar Bears / Documentary (English/HD).
From the Wildlife Conservation Society:
Going to Need a Tougher Buoy
January 5, 2016
The time a polar bear temporarily sunk important research equipment
The top of the world is warming at almost twice the rate of the rest of the planet and scientists there are grappling with what that means for local wildlife.
For instance, as the ice retreats and shipping in the area increases, how will it impact resident marine mammals?
Answering such a question in the far north comes with unique challenges, though.
Our Arctic Beringia Program faced one such obstacle last year. As Dr. Stephen Insley detailed on WCS Canada’s blog, the team had placed a buoy in Sachs Harbor, in the western Canadian Arctic, to record underwater noise.
At some point, before Insley and the team could retrieve the data they had recorded though, the buoy disappeared underwater.
Suspicion fell on polar bears.
The disappearance coincided with a sighting on the outskirts of the nearby town. The local safety officer had chased two bears out of the area and one was seen swimming off in the direction of the buoy.
Eventually, after hours of dredging the water to no avail, Insley and a local colleague (who also happened to be said safety officer) struck research gold—they hooked onto the rope that was attached to the buoy and pulled it up.
On it, they had their smoking gun: water poured out of the busted float from a pair of teeth-sized holes, which were separated by roughly the width of a polar bear‘s jaw.