Skateboarders are always trying new tricks and some are so intricate--involving subtle board flips underfoot, etc.--that the average person does not always know what the athlete is doing.
But viewers of the above footage will know exactly what Adam Miller is doing: a fully extended back flip from one skateboard at the top of a mini-flight of stairs to another skateboard waiting at the bottom (be sure to check out the slow-motion footage).
It's described by the Ride who filmed the footage as the "first-ever gainer back flip from one skateboard to another down six stairs!" and that's probably a fair statement.
Check out the perspective from the legendary Tony Hawk, and his reaction, via his post on Vine. He wrote, "Here's something you don't see every day... or ever."
To be sure, it's an impressive trick that translates well to the mainstream, and one can only wonder how many painful falls were endured before Miller stuck the landing.