I've been using the same trick to bend and braze aluminum angle and tube, though I hadn't thought of doing an outside radius. That's cool.
Maybe I need to chill out, but the way the guy in the video used the angle grinder to do the radius made me nervous; I'd worry about the possibility of shattering the cut-off wheel. Especially the way he's kneeling in front of the work piece with his nuts exposed.
Indonesia man, things are pretty loose over there. Health and safety is literally a total non-starter, and yet these guys seem to have some kind of sixth sense when it comes to pushing the envelope. It's weird.