Hi Johnny,
If I were trying to do what you are doing I'd step back a bit and consider that most .mp4 is mpeg4 HD and DVD is a subset of the the mpeg2 Standard Definition.
So, what I would do is consider some of the programs that can convert from mp4 to "mpeg2" and then try to burn a CD.
Quicktime Pro ($30) can do it. I have video editing software so I usually do format conversions with dedicated apps, so I don't have a knowledge of what free apps actually work.
I consider QuickTime Pro and essential swiss army knife for times I don't want to use a special app.
In any event, check the apps you have for the possibility of using a two step process. Convert the mp4 to 720x480 SD mpeg2 (hint: mpeg2 is actually a "definition" with lots of codecs but most of the easy to use apps use the mpeg2 choice to denote the specific codec used by DVDs) then use the mpeg2 file as the source of for your DVD burn.