Stephen,

Sometimes you stumble upon an absolutely untranslatable term. These words - Мишка/Михаил Потапович - bring memories to any Russian who was read or told folk tales as a child. In Russian tales, the Bear sometimes is not only clumsy, but also easily fooled; but sometimes he helps the hero out of great difficulty. He is hardly ever mean (unlike the Wolf) or crafty (unlike the Fox).

Try as you might, there is no there is no cultural equivalent for the American viewers of the documentary. I thought about Yogi Bear or Berenstain Bears, but it's simply not the same, and will just puzzle the audience: what Yogi Bear/Berenstain Bears are doing in a Russian documentary?

Therefore, I respectfully suggest that you simply transliterate the proper name and add "The Bear".

Good luck!