I don't use Nero, but to kick things off I can tell you the basics which might get you going in the right direction:
Where has your movie file come from, what format is it in? It MAY need converting before it can be put onto a DVD. My normal route is to convert digital .avi files (that's what I get off my video camera) into MPEG2 files using separate software. My burning software (Roxio) then puts the MPEG2 files onto a DVD; but it's not a simple case of drag-and-drop the files. You have to use the function in your burning software which is called "create a DVD" or somthing like that, so that the burner programme will automatically record all the other files your dvd player needs to enable it to play your video.
Thanks for asking this question. Although I don't have a DVD writer yet I am about to buy one. I also noticed the only option in NeroBurn 6 was "miniDVD". I asked what a miniDVD was (in another thread) as opposed to a 4.7gb DVD. Are they the same. Put into My Posting to keep an eye on the resonses before I buy.
As you do not have a dvd recorder in your system then nero 6 or any other software won't give you the options available to a dvd burner. If you did not have a recognised cd burner on your system the same would apply.