No, this isn't footage from a particularly grotesque alien invasion film. It's stroboscopic footage from a laryngoscopy, showing us what the human vocal cords look like in action.
If koalas have any reputation at all, it's as quiet, cute marsupials that spend all their time eating eucalyptus. But male koalas unleash loud, deep yells that sound like the mating call of some massive beast. That's exactly the point.