To be honest, I have no idea if a video - edited or otherwise - could be re-inserted into the original DVD structure. I would imagine that Ifoedit might make this possible. I guess it would all depend on what program you are using to re-intergrate the DVD files. I know that DVD-Lab Pro can recompile designated parts of a DVD project, so that you don't have to redo the whole thing for a few small changes, but that's a project created from scratch.

Worst case, you can try just adding those four seconds to the end of the video.