Right away we have to say that there is no evidence that this black feral cat killed the Shy Albatross chick.
What annoys me slightly is that the video has been published on a bird website (birdguides.com) with, it seems to me, the intention of stirring up resentment at the predation of birds by feral cats in Auckland Island, New Zealand.
The author mentions that feral cats have been blamed for the decline or extinction of some bird species in New Zealand. They don’t go into detail. The author needs to go into detail because often there are some interesting facts which are conveniently forgotten by ornithologists.
Further down the page the author admits that they don’t know if the cat killed the albatross.
“Unable to say if it was just scavenging or had killed it…”
Feral cats tend to scavenge when they really have to. They’d rather kill and eat because they know what they are eating as a dead bird may contain toxins. I sense that it is more likely that the bird died of some other cause than a cat attack.
The video is very unusual though, and perhaps unique, which is why I have published it on the site. There are few records as far as I am aware of feral cats attacking and killing albatrosses.