How do you sing/scream raspy?

I'm not talking about death metal vocals I mean something like this.

http://www.youtube.com/watch?v=HMb9Uf-R074

Go to minute 1:15 she's kinds screaming a bit raspy from now on and at
1:40 she's really screaming.

Does anyone know how to do this and can actually explain it to me? if
you have some video that explains it it would be awesome too.

Thanks