Whatever the name is, I can't find a way to do this thing... it sounds like you mute all the strings except the one you want to play, then you strum all of them, making a more agressive sound.

He uses that a lot throughout this video http://www.youtube.com/watch?v=Z9i5dcUNBi8
the first time he does that is at 0:55

I thought you were supposed to mute the strings with your palm but sometimes he lifts his picking hand all the way up... can someone explain how to do that? And if there is a name for this technique, please say it

It's called a rake, I believe.

And yes, you do just mute the strings with your picking hand
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It's called raking, Stevie Ray Vaughan and most blues guitarist used this in everything. It gives more depth to a single note and makes it sound fatter
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