This is an interesting video snippet that has been making the rounds of the internet lately. While brief, it is particularly edifying. The salient and interrelated questions are: what precipitated the outburst, why doesn't it develop into an all out fight, why are their jaws agape, why do they rise up on their hind legs, what is the criteria which resolves their "dispute"? I will add my interpretation shortly from the perspective of an immediate-moment lens, as well as contrasting this to the calming signal theory and the dominance manner of interpretation.
--Read the follow-up post here.