I think everyone's looking at Instagram's new videos the wrong way.
What will make Instagram successful in video isn't some specific product. Rather, it's the way Instagram videos play well on Facebook.
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Everyone's comparing Instagram to Twitter's Vine app. Both allow users to take short video clips. And so it's easy to tick off a list of explicit product features—max video length, stabilization, filters, and so on—without considering which ones people will really use.