As the paca is a nocturnal animal, this paca is probably injured either by having fought with another paca, some other predator larger than it or was bitten by a snake and is under the effect of the venom.
You can clearly see that the paca is standing, kind of stunned and slow, and anyone who has seen a paca running knows how fast they are. In addition to running a lot, they swim and dive very well.
Ferrets are formidable hunters, but we have to make the necessary observations. An adult paca is twice as big as the one in the video, which leads us to believe that it is a very young individual.
