How do Youtubers use copyrighted material in their videos without it being taken down?

How do Youtubers use copyrighted material (content which is not theres) in their videos without youtube taking it down?

- I mean Pewdiepie takes videos of games.
- Shane Dawson uses background music from songs and pictures from the internet.
- When people make impression videos, they use pictures from google images.

I know that if you want to use material that is not your own, you have to get permission from the person who owns it.
But I doubt that Shane Dawson and what not ask permission for EVERY photo/song/video/etc they use.

So how do they get away with it?
Asked Aug 20, 2014

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