The video below is interpreted as showing a dog playing the role of peace maker by stopping things between two other dogs before it gets out of hand.
While the "Good Samaritan" dog here does indeed interrupt the two other dogs, is that its intent? Because if such an interpretation were correct then we would expect to observe "splitting" behavior occurring uniformly across the spectrum of canine temperament types rather than being typified by a particular kind of dog. The "splitters" I've known are always dogs that are more easily knocked off balance and tend to keep out of the rough and tumble in play in general. They are typically quite playful, but they are more sensitive or defensive than others and often tend to stay near of orbit the handler. Note how this dog came from nearby the person with the camera and hasn't to that point seen interacting with the other dogs. While this is but a brief snippet of video nevertheless I'm not drawing my conclusions based on You Tube videos. If I were selecting from a group of dogs asa personal or service dog, I would disqualify such a dog. Not that I don't like these types, but they're not a clear enough channel for demanding work.
What's going on within this particular dog is that it is holding back, and when other dogs begin to manifest intense displays of energy, this dog's DIS is triggered and it now has the chance to express INDIRECTLY what it holds back from expressing DIRECTLY. So intense displays of energy particularly unbalance such dogs but simultaneously trigger stuck energy. And since every interaction is a transaction of momentum, the bottom line is that the splitter wants to get a piece of the action and so we see how it immediately tries to play with one of the "troublemakers" once they've disengaged from the other. It begins to respond DIRECTLY because it now feels liberated from its attachment to the handler.
The reason I'm such a stickler on these matters at the risk of seeming the Grinch who stole Christmas, is that to accord the role of peacemaker to the "splitter" means we will miss the group flow system that is really the architect of collectivized behavior. When two dogs fight, they are not transferring emotion coherently, instinct and pain memories are getting in the way. And that in any group there is the low threshold yet high capacity individual that would jump into that friction (if a high prey threshold dog got involved the potential for real violence could erupt) so that flow emerges, speaks to the nature of emotion itself, the intelligence that is embodied in the very principles by which nature is organized. And to miss that point is a real shame to my eyes.