Copyright protects the expression on the DVD, not the physical disc itself or the raw data on it. A commercial DVD probably has dozens of copyrights. The script of the movie is protected. Every frame of video and every snippet of audio is protected. The music of the songs of the soundtrack are protected. The recordings of the songs of the soundtrack are protected. The text on the back of the DVD box is protected, as are the pictures on the front and the liner notes (if any) inside. The CSS encryption on the disc is protected by copyright (only the author of CSS is allowed to sell it to the movie studios) and by the DMCA (it's illegal to break the encryption). And so on.

You need a legal right to copy or otherwise use ANY portion of any of those things. Fair Use doctrine provides you with some of these rights--even to copyrighted works. For example, you have the right to use portions of the movie for purposes of criticism or parody, the right to "space shift" the DVD (ignoring DMCA issues) to another medium for backup purposes, etc.

But the law doesn't think of copying in the technical sense of "is it an exact copy." Rather, it looks at whether the protected expression has been misappropriated. The guy selling bootleg DVDs on the street that were shot with a camcorder in the theater is violating the filmmakers' copyright just as much as the guy selling bootleg DVDs on the street that are perfect bit-for-bit copies of the commercial disc.