A brief summary of the video. The guest, Jon Danaher thinks that combat or fighting comes down to skill, "physical attributes," aggression, experience and ability to initiate combat. The lion has an abundance of all. A lion is an ambush hunter that has to face constant danger and challenges, including taking down large and dangerous game like cape buffalo. Lions also have to fight within their own pride and this often to the death. The Grizzley bear would have the edge over the lion in a confined space due to having more weight and better endurance. Also, that the Bear may be able to shake off/tear away a bite to the throat by the lion. It was interesting when he mentioned that Leopards commonly take out Gorilla's by biting a major artery in their leg and then letting them bleed out.
He also mentioned that the bear does not face any real competition from other species that can kill them in their natural habitats, but do sometimes run from mountain lions.