If you really wanted to make a back-up copy of a DVD, you’d never convert it to AVIs. AVIs are fine for PC monitors, but are pretty dismal when viewed on a TV screen. These AVIs make illegal distrubution over Torrents fastier and easier, but the quality of these files once converted back to DVD is nowhere comparable to original or what you’d get from a DVD Shrink backup. DVD Shrink makes excellent copies which you can either leave on your hard drive or burn to a DVD-R.

Also, at first glace, the tutorial you link to is for people who want to make AVI copies of DVDs. The only reason you’d want to do that is to upload them for Torrents. AVIs will do you if you want a bootleg copy of a DVD and you don’t care too much about the quality, but AVIs (and Xvid AVIs), as nice looking as they are sometimes, are still heavily compressed compared to the original DVD. They might look okay on your PC monitor, but try playing them on a large TV or an HD TV, and, campared to the original DVD, they look like crap. Still, for a movie that doesn’t cost you anything, I guess it’s good enough.