Ever wonder how strong a macaw's beak is? Have any doubt that a macaw could easily break steel-welded cage bars?
I think you can see where I'm going with this post...
Please note that the person uploading this video wants to make clear that this cage was only a temporary cage (because Kaiser the Hyacinth Macaw broke his first one, too!), so be aware that this isn't an appropriate sized cage for a Hy. But when such a huge bird destroys his cage, it's not exactly easy (or cheap) to find a temp cage quickly. A cage with broken bars is a HUGE safety hazard, so once this happens you can't keep your bird in it anymore.
Kaiser's owner warns other would-be macaw owners to make a smart investment in the best cage you can buy the first time around, because buying several "pretty good" cages is way more expensive than just buying the best cage the first time around. For a Hyacinth-sized bird, you will definitely need as big of a stainless steel cage as you can find, with very thick bars (or maybe even a primate cage, seriously).