It’s Vine vs. Instagram in the great video showdown of 2013If you love the artsy brevity of Vine videos—but struggle with finding ways to jam shots of your jewels into its 6.5-second format—you might want to consider a new product from one of social media’s most popular names. Instagram, the ubiquitous mobile photography app, recently launched a video service, Instagram Video, offering 15-second video functionality with full-on editing capabilities.Moving into video is an organic evolution for the social juggernaut, and also a strategic response to Vine’s brisk ascension. “Instagram saw the adoption of Vine and wanted to break into that,” says Steve Garfield, author of the video-in-social-media–themed book Get Seen: Online Video Secrets to Building Your Business. But ultimately: “Instagram came out with video because they were tired of hearing competitors called ‘the