That's two hummingbirds in our tree—can you find them both?
They are both females so what I took to be playing may have been territorial behavior, but it looked a lot more friendly than that. They were in our yard together many times today for prolonged periods, sitting in the tree and pipping, flitting through the gardens and around the feeders, still pipping, and they never appeared to make physical contact, but they certainly were fun to watch. Apparently we have the destination yard for hummingbirds.