Don't scare your cats for fun.

There seems to be a trend in posting videos of cats being scared by their humans so they can make it into a "funny" video. Sickening. These people don't understand their cats at all. Cats are not only predators but also prey animals and have enemies in the wild. To scare them where they normally would feel safe, their house, and especially when they're eating and vulnerable, is cruel.
Here is a link to a page where it is explained by a vet why scaring your cat intentionally is wrong.