It seems like just yesterday (about three weeks ago, actually) that we told you about Vine’s massive victory over Instagram in the Twitter realm. At the beginning of June, Vine shares finally surpassed Instagram shares for the first time – that means that more tweets containing a vine.co link were being sent out than ones containing an instagram.com link. It was a big deal for Vine – the just 5-month-old video sharing app with barely 1/10th of the users of Instagram.

Of course, it didn’t mean that Vine was suddenly more popular than Instagram. There are plenty of reasons for Instagram’s Twitter shares to diminish – the disabling of Twitter Cards, mainly. But it did show that Vine video was definitely a force worth paying some attention.

Oh, what a few weeks can do.

Here’s a chart, courtesy of Topsy analytics, which shows a distressing downward trend for Vine shares on Twitter – one which started around the time a particular competitor came on the market.

What happened around June 20th? Instagram unveiled video, of course. And since then (even a little before – anticipatory jitters?), Vine shares have plunged. As it stands, tweets containing vine.co links have dropped to under 1 million in a 24-hour period – down from over 3 million at their peak.

It looks like Instagram Video is stealing Vine’s mojo.

Interestingly enough, Instagram shares on Twitter haven’t really spiked. That’s easily explained by the fact that Instagram is a more self-contained social network that Vine – plus that aforementioned Twitter Card thing. What’s the point of sharing Instagram content on Twitter if it won’t show up inside tweets anymore?

We know that Instagram Video was an early hit. In the first 24 hours of availability, over 5 million videos were shared.

Today, Vine updated their Android app to add front-facing camera support. I’m not sure that enabling easier selfies is enough to put Vine back on an upward trajectory, however. What do you think? Still using Vine? Or have you switched over to Instagram Video?