A number of Twitter users have reported that soon after the announcement, they received an e-mail from Twitter which laid out all of the reasons why they should be using Vine, and what a great product it is. The e-mail came with the subject: "Vine: A new app for creating short, looping video" and a link to download the app.
It's not surprising that Twitter would be a bit worried about the arrival of Instagram video. Vine has seen solid growth, but it has the limiting factor that it is a separate app from Twitter, so it's growth has had to happen on a slower pace. And, Vine only recently made the leap to Android, at which point it announced 13 million users. On the other hand, Instagram already has 130 million users, and every one of them just got the upgrade add video to their experience.
source: The Next Web