Safe areas are guidelines, nothing more. They're the there to help you know where to place your content so that your video and menus will be visible on most televisions. It is not the safe areas that "cut off" your content, but the television itself.

As such, sure, you can adjust your safe areas (Options > Preferences, Editing tab), but it will have absolutely no effect on your video. The default values, however, match the area visible on most modern televisions.

99.9% (give or take ;) of all content you've ever seen on television (including VHS and DVD) was larger than what you actually saw. As a content producer, it's your job -- from the shooting stage to the DVD menu creation stage -- to be sure that the important content fits within the safe areas. At the same time, however, you don't really want dead air (eg, blackness) around the edges since the actual amount of area cut off varies from television to television. Also, someone watching your DVD on a computer will get the whole screen including the blackness.

So, ask yourself, this "ton of video" that gets cut off -- is it essential for the viewer to see? If no, don't worry about it. If yes, you should go back to your editing app (Vegas, I presume) and fix your video there in a way that's appropriate.

Rob