Either make a perfect bit-for-bit ISO of the disc and put that on the hard drive; VLC can play movies directly from ISOs, and doing so would be perfectly legit because you're not dealing with cracking the CSS encryption on retail DVDs. This is the recommended method, actually - at least by me.
The second involves software that I'm not going to name anymore and not even hint at because the name itself lends to the very process of cracking the encryption and that's something we're not supposed to discuss around here.
www.doom9.org or www.videohelp.com would be the two primary places online to get more info about doing what your friend wants done. Personally I'd just say use the first method above: he'd have a perfect copy (including the encryption which never gets cracked) on the drive, and VLC will treat that ISO as if it were the physical DVD in the optical drive with all the bells and whistles too.