In our May 4th milk* email, we let you know about how much fun we were having with Vine, Twitter’s wildly successful App that has allowed 13 million users to post 6-second videos of almost anything. Well, Facebook won’t let Twitter own the hash tag or the shot-format video category either. Last week Facebook announced that their photo-stylizing site, Instagram will now allow users to post up to 15 seconds of video. It’s easy to use and offers little differentiation (aside from duration) from Vine. It seems the only reason for Instagram Video is steal some of Vine’s thunder. Who will rule? Stay 15-second tuned.