This video is titled "Rottie Fight". I watched it and in my opinion they are playing. What do you think? Playing or fighting. I think because they are rotties if they were fighting they would tear the s*!t out of eachother.
Bear in mind they aren't growling. Some people just seem to think that because the are rotties they are vicious bastards and would be fighting. But they are really soft at times. Anyway this is cute to watch :D