ELI5: Explain Like I'm 5

Viacom International Inc. v. YouTube, Inc.

Viacom is a company that makes TV shows and movies. YouTube is a website where people can watch videos.
Viacom said that YouTube allowed people to upload their TV shows and movies without permission, which violated copyright laws. Viacom sued YouTube for a lot of money because of this.
YouTube said that they didn't do this on purpose and that they were trying to stop it from happening. They also said that they had a tool that helped them remove copyrighted videos when they found out about them. The court had to decide if YouTube was responsible for the videos that people uploaded or if it was up to Viacom to find and report them.
In the end, the court decided that YouTube wasn't responsible for the videos that people uploaded because they had the tool to remove them and because they didn't do it on purpose.