You can get around reauthouring if your DVD player supports MPEG formats. Since your video (I assume) is playable in VCD it must conform to the following specifications:

1) the video file has been encoded in "MPEG-1" format
2) the video portion is 352 x 240 @ 29.97 HZ or 352 X 240 @ 23.976 HZ (NTSC) or 352 x 288 @ 25 HZ(PAL)
3) the audio portion is 44.1KHZ stereo @ 224 Kbits per second

If these requirements have been met then NERO will put this into a "VIDEO_TS" folder and burn it onto a DVD. I play MPEGS in this fashion all the time on my DVD player