Advertising and public relations agencies everywhere have been buzzing about Vine for months. It has certainly been the shiny new social media tool to watch.

With 13 million users on iPhone in just five months, and the launch of an Android app, Vine looked unstoppable.

Then on Thursday, Instagram launched its video platform, instantly undermining Vine's dominant position.
Here are just four reasons why:
1. Fifteen seconds versus six seconds.
It can be a lot of fun to come up with six-second Vine videos, but it's also challenging. One can accomplish infinitely more in a 15-second Instagram video. The extra nine seconds gives the creatively-challenged a much better chance to create great content.
2. Losing the loop.
If you watch a Vine video for 18 seconds, you kind of want to jab your eyes out. That's because you've seen the same thing three times, without clicking replay. The automated loop feature is a fun novelty, but it's just that: a novelty. While it can be used creatively, it also gets old. Instagram videos are 15 seconds and they don't loop, which will appeal to more mainstream users.
3. Integration with Facebook.
Every social media nerd I know got really excited to hear that the number of Vine video shares on Twitter surpassed Instagram's. But that only happened because Twitter killed Instagram's "native" pictures in the platform. This meant that if you tweeted an Instagram photo, your followers had to click off of Twitter to view it. In addition, Twitter blocked the ability to tag Twitter users in Instagram. Vine, however, is native to Twitter, and can be viewed right within the platform. The extra clicks can be the death of any piece of content, no matter how compelling. Now, it's payback time for Instagram. Its new video feature will launch with its existing user base of 130 million people, and will have seamless sharing and viewing with Facebook's 1.1 billion users. Twitter's user base is half of that.
4. First-mover disadvantage.
Instagram could have launched video five months ago when Vine came on the scene. Instead, it took its time to build something beautiful. Instagram watched what Vine did and improved upon it. The user experience is clean. It removed annoyances and added its signature filters, and the end result looks great.
It's worth noting that early Vine adopters like Urban Outfitters have, within just a few hours, produced Instagram videos. Brands go where the people are, and while there are people on Vine, there are far more on Instagram.
Vine is shiny. It's fun. It's "cool." And Vine will continue to exist. It's a fun, quirky video tool that is perfect for short, funny clips, especially on Twitter. But Instagram is a force. It launched a smart, user-friendly video app, and will capture a significantly larger percentage of the video-taking, content-creating market.