Those chickens in the video were made by genetic engineering, yes, if you consider selective breeding to be genetic engineering. I'm not sure if anyone has made an actual GMO chicken, and if they have, I don't think it's a skinny game-looking breed from Brazil.
I don't know for certain that Malays are healthy, but I know they're a really old breed, so I suspect they're at least not bad. They're just big by chicken standards. It helps that they're skinny, too- if they were big hefty things, they might have more issues, but they're not terribly heavy.