For one, don't start talking about ripping here, PERIOD. It's illegal and makes you sound rather stupid when you start posting stuff about it on a public forum...
As for the question, it's rather basic. Take the reply image, for example... Say you want to get rid of the text... You CAN, but you basically have to redraw the picture. A video works in the same way. Once it's been compressed and everything, it's that way for good. A video simply is a bunch of pictures. So if you find someone willing to clean up about 200,000 pictues, more power to ya
If you're wondering about say DVD's, the subtitles there are added in though the DVD player.