Thanks all for thre help so far. But your replies don't answer my questions. I'm sorry.
I was talking about decreasing file sizes, in order to save some space. I was wondering if it was possible to (as an example) decrease the size of an 1Gig movie file to 750mb at least, taking of 25% of mb space. And without loosing quality. When downloading porn I'm used to cut out the best pieces of the scene, but I still want to try to have little storgae space.
Kind regards