Backpack feed systems are nothing new to light machine gun design, these examples dating to the early days of the AR10 and AR15, in addition to modern Russian concepts, and even a Libyan take on the idea.
The Prime ManPack/ Machine Gun Backpack from Aleppo Systems is a current Israeli take on the concept. Earlier in the companies history it appears there were some patent design issues, but the current version appears to be a vastly different system, mostly using polymer components for the feed chute. It is also designed to have the entire ammunition box reloaded by an assistant gunner while being worn. The company also envisions the box being strapped in a vehicle where reloading multiple boxes would be more practical.
This is a promotional video of the system in action:
Aleppo System representatives said that the backpack was currently being tested by IDF units in addition to showing videos of the systems in IDF hands in the field trials.