Instagram (FB) will add video-sharing support on Thursday, TechCrunch reports. Such an update would be aimed at Twitter's Vine 6-second video-sharing app, which has racked up 13M+ users in just 5 months. An Android Vine app launched earlier this month has already passed Instagram on Google Play download charts. But with a base of 100M+ monthly users connected via both its own social network and Facebook, Instagram should be a formidable rival. TechCrunch notes adding video support could also appeal to marketers if/when Instagram begins showing ads.