Actually its a thing called the NS Patriot Gun that is only available during the 4th of July. Last time I checked it will run you 700 SC to get.
The description of the video states it wasn't the flaregun. The pattern's different anyways. Cool effect, though!
We had a friend or two on the Dev team/QAA team who was oh so kind enough to allow me to put it out in a video. As far as I know, they're in the game files, but for a reason I'm not privy to, they haven't released anything about them to the public. Clearly they're letting you all see it now, so you might be able to find it on the marketplace in the future, but don't take my word for it.
