This teaser for Assassin's Creed III is different from the blitz of video we've been getting as the threequel nears release. In the clip, you see a bit of Connor's life from before he became an Assassin. The scenes of him running through the forest look beautiful but get harshly contrasted when he comes home and find his village and loved ones burning to the ground.
Those moments really drive home how Connor is a different type of lead character for the next Assassin's Creed. He doesn't come from a life of ease like Ezio and wasn't born into the Assassin's order like Altair. And the fact that his catalyst for becoming an Assassin is tied into the tragic history of Native American in the United States will likely make his story more poignant.
And, in what may be another significant shift, it really looks like Connor slashes the throat of an American revolutionary soldier in the sequence from 0:46 to 0:48 in the trailer. It's quick, but the coat on the victim looks blue and not red. See for yourself.