Photos allow you to discriminate which moment in time you want to convey to people. You can take and retake photos until you distill it to the right scene. Dead simple postprocess editing, e.g. filters, allowed you to enhance that even further.

Videos don't work the same way. Trying to distill the zeitgeist into a video is (24FPS * 15sec) times more work. Without a rich set of postprocess editing tools, i.e. what filters did for photos, that are equally dead-simple, the fantasy-aspiration of what instagram did for photos simply isn't there.

Sure, the trailer instagram showed for the introduction of videos had the same emotional and fantasy components in it that filters brought to photos, except they did a crap ton of postprocessing work on it to get it to that stage. Contrast this with when they showcase photos and filters - they must have done little or no work. Unless the app itself can create the level of videos that instagram showcased, instagram video has brought upon itself the death of fantasy.