With that being said, I didn't see these kittens fainting, instead I saw them being placed on a highly polished wood floor and the intimidation in their eyes.
What likely happened in the original video is that once on the slippery floor that the kittens were obviously afraid of, the artifical noise used to startle them caused them to react and attempt to bolt but not having any traction of the floor, they simply fell down.......
Watch the video real close and observe their hind paws. In virtually every instance you will see them slip on the floor which results in them falling down.
And by the way, they also appear to have been declawed...........
Since they were kittens, if they were indeed declawed, it is quit likely that the surgery was very recent to the video being taken which would explain why they are approaching the floor with extreme trepidation........