I know it sounds silly but somebody asked me what's the extension of home usual DVD files and I couldn't answer. I've never burned one of these so I ask... Thanks!
To expand to what Jet said: DVD video is mpeg2 so you'll want .mpg or .mp2 extensions. You can usually burn a .mpg straight to DVD and it will play in many home DVD players (without menus).
But if you're trying to copy a DVD forget it. Without special software it's a real PITA. Lengthy directions at http://www.dvdrhelp.com/dvdripping .
You can also check out digital-digest.com for a ton of info on the way a DVD's put together.
FWIW, the authoring software might insert a bunch of what will appear to be dummy .vob files [very short with no easily apparent content], and .ifo files that are more or less the directions for the DVD player or software on how to put the whole thing together. Apparently a bit of this arcane knowledge can be useful not just for ripping, but when things go wrong or you're trying to fudge your way around a less behaved app then DVDA/