Pretty self-explanatory stuff. Don't smash a pregnant spider. Especially a black widow spider that spawns a hundred tiny black widow spiders.
But really though, something seems off. The amount of spiders that come out of the big one doesn't seem right. If you watch the video in slow motion, where the spider is and the splat don't match up, and the initial mass of baby spiders is a lot bigger that the original spider. We're calling this one fake.
Bonus points to the genius who circled the only thing in the video with a red circle.