I suspect he may refer to "heat". AR barrels typically are on the light side of the spectrum; sustaining automatic fire with this firearm won't last. At best you'll get to keep it running on bursts; in which case the belt increases ammo cap.
It's one of those things that's fun and cool to see people get creative in "making things work", but at the end of the day you have a civic with a fart can to make it sound like a muscle car. It won't perform the way you want a muscle car to perform and is really just a pony in a dress. Why not get the muscle car instead?
Cool idea, cool engineering, definitely fun idea; but impractical for true use. Military and Private Security forces are more likely to spend less money and have a weapons platform that's far more superior for the role that this tries to fill.
Also; will probably be prohibited import as its modifying a firearm; not a straight up factory build. I'm not sure what the regs are on belt fed in Canada with the whole mag cap either ((but I know there are some legal belt feds out there)).