You'll recognize a cinemagraph the moment you see one.
They're hypnotic, mostly still images with artistically rendered, subtle motion—kind of like the moving photographs and paintings in the Harry Potter films.
Although there are no marketing silver bullets, cinemagraphs are fairly shiny and new, and they are still rare enough to have impact on your audience.
Here's a beautiful example I couldn't stop looking at when I first saw it:
The History of Cinemagraphs
Cinemagraphs were invented in 2011 by photographer Jamie Beck and Web designer Kevin Burg for Fashion Week in New York. The response to these magical images was so overwhelmingly positive, that the pair was able to build a business around them. Fashion cinemagraphs were soon being used by heavy-hitters such as Vogue's Anna Wintour.
One of their first major commercial projects, four Instagram posts for shoe designer Stuart Weitzman, earned over 1,600 comments and 60,000 likes from fans within a few days. The content took advantage of the platform's new-at-the-time video looping feature.
Even with new developments in consumer-grade video apps, such as Instagram's Boomerang, Beck's and Burg's cinemagraphs stand out for their craft and composition. Here's a (low-resolution) GIF version of one of them: