In that case you will need a DVD-authoring tool. The file format and contents of a playable DVD-Video disc are quite different to simple mpeg data files.
I use Corel VideoStudio myself, but there are others. Corel is an editor with an inbuilt authoring tool. What sets it apart from many other tools (editors primarily) is that it doesn't neccessarily force the data to be re-encoded (which is ALWAYS a lossy and slow process). If it encounters compatible data and it will fit the target disc, it just copies the existing data into the new file (for edits) and/or the neccessary file structure (for mastering).