Adrian Weckler interviewed Mike Krieger, co-founder of Instagram, for Independent.ie out of Dublin. Regarding longer form video Krieger replies:
What we have right now is a minute. If we introduce longer video, we have to make it fit into the flow of Instagram in a way that makes sense. I think what might point the way is the people who use video today on Instagram. I meet these digital creators who are producing video for Instagram and they'll often do a short cut for their Instagram feed or for Stories and point to a longer video. Often that lives on other platforms because you just can't post them on Instagram. But the idea of a teaser plus the full piece of content, if you were interested in it, might be a future piece.
I don't know exactly what would make sense for longer form video on Instagram but so far they've been making great choices. I think just being able to play videos full-screen would be enough for me. I think it'd be just fine to see longer form video on my timeline with, perhaps, the first 15 seconds as a preview or something. But I'm unsure.
Another takeaway from this interview is how Instagram has always talked about how it ripped off Snapchat. I really love the candor. They have always come right out and said that Snapchat was first. And then they back up why they've brought that medium to Instagram. The reason he gives is both obvious and apt; because people were already doing it by creating second accounts to share more regularly on. Now they don't have to do that.