So while this video might evoke a strong emotional response, it is just an anecdote and not actually evidence one way or the other for human-caused climate change.
Of course, human-caused climate change is obviously real, but it's not OK to use bad arguments even if your conclusion is correct.
EDIT: To clarify further, I am not disputing that polar bears are not being harmed by climate change, or even that the particular bear in the video is not starving because of climate change. I am merely pointing out that one could produce a video of a starving polar bear both in our world and in the world where climate change is not happening, because wild animals starve all the time.