Since the invention of motion pictures, video science has proceeded steadily in a single direction: upward. Better resolution. Higher frame rates. Richer audio.

Yet online, something weird has been going on. The hot thing in video these days isn't big, sharp and smooth. It's tiny, jerky and often low-res and mostly silent.

Exhibit A: The animated GIF. This format—which creates small, looping, silent videos with limited colors—was invented by CompuServe in 1987. Before Flash, QuickTime, AVI or other modern video formats, the animated GIF was an early way to put moving images online. It popularized the dancing baby, the waving American flag, funny cats—and much of Myspace.

Weirdly, 26 years later, this ancient, limited format is still around. In fact, these jerky snippets are more popular than ever. They're the dominant currency on popular “What's cool online” sites such as Tumblr and Reddit. They're still passed around in e-mail signatures. It's baffling, really—as though the Betamax were suddenly making a comeback.

Exhibit B: The Nikon 1 cameras, that company's flagship midsize camera line. Their mode dials, which on most cameras have various scene presets, offer only four choices—and one of them is Motion Snapshot, which captures a one-second video clip without recording the sound. Somehow these cameras have become best sellers. Nikon must have known what it was doing.

Exhibit C: Vine, an iPhone app that lets you capture six-second videos and then post them via the app's own social network or on Twitter or Facebook.

Who would go for such a limited tool? Everybody. Vine became an instant sensation. Hundreds of thousands of its short videos flooded the Web, companies used it for ads and contests, and The Daily Show with John Stewart made fun of it.

What is going on? What happened to the quest for better, bigger, brighter videos?

Theory 1: Technical limitations. Big, beautiful video takes up a lot of bandwidth, which costs money on your cell-phone plan and takes time to load on other devices. Small, jerky, short video gets the message across but loads almost instantly and doesn't run up your bill or waste your time.

Animated GIFs have another advantage: you can post them almost anywhere, even on comment boards and profile pictures. And after all these decades, they play in every browser and on just about every gadget on earth—which you can't say for more modern formats like Flash.

Theory 2: Limitations foster creativity. Twitter is the standard for this concept: hard-coded limits force you to be more concise, more creative. Most people don't complain about Twitter's 140-character limit; they embrace it. That brevity is what helps make Twitter a force of nature.

Surely compression is a key to Vine's success. A six-second video may seem very easy to shoot, but it takes thought and ingenuity to tell a story in that time, and some of what people come up with are masterpieces. You can also compose a Vine video of many shorter shots, so some of the stop-motion Vine videos are especially impressive.

Theory 3: Video is the wrong comparison. In the end, maybe the growing popularity of the short, crude video snippet is no mystery at all. True, these clips look limited when compared with the video images we see in theaters, on TV or even on YouTube—but maybe these aren't so much stripped-down movies as they are live-action photographs.

A photograph is intended to capture a single moment, to present it for thoughtful examination. In the end, that's what a one- or six-second looping video does so well—it's just that it expands the scope of the still image, explodes it to an almost infinite variety of new possibilities, moments and stories. Maybe the micro video is best considered an improvement on a still picture, not a downgrade from video.

Or maybe the online micro video is neither photo nor video but something in between, with artistic merits all its own. Maybe it's simply a new form of expression.

It just took us 26 years to recognize it.

Watch 12 micro video apps that aren't Vine: