Converting DVD to hard drive?

[classic_09]

Ive seen so many people on youtube use clips from movies and put them into a video. I know in order to do that you have to rip the dvd onto your hard drive. But when i try to do it, it tells me that i cant do is since the movie is copyrighted and that ill need some other program to install in order to de-crypt it? Ive tried different programs and downloads and cant figure out what to do..
thanks in advanced, everyone.