Although it is hand-cranked to fire, the name must be a misnomer because it isn't a Gattling gun at all. A gattling Gun has a cluster of revolving barrels on an axis that fires each barrel sequentially as it rotates to the top position.
Anyway, whatever this is, it's pretty cool. This looks like a modern rendition of something I saw at a gun show 20 years ago. I've also seen a version of this that uses a pair of AK barreled actions. It looks awesome with the 75 round drums installed!
There was once a 1/2 scale version of the 1919A4 Browning equipped with a tripod, that fired .22LR fed with a real cloth belt. It was made by Tippmann Arms (the same company that makes paintball guns) and it was VERY expensive when new, but VERY cool looking. I just did a google search and found a .22WMR version selling for only $5500.