DeVeDe Cannot Create Directory Structure

I’ve been creating DVD’s from my DSLR video for a few months. The most effective method has been to convert the videos from HD to DVD with FFMPEG:
ffmpeg -i video.MOV -target ntsc-dvd video.mpeg
then import them into DeVeDe and let it create the DVD disk structure and menus. If I let DeVeDe convert the videos, the quality is horrible.
The last time I did this, however, when DeVeDe was creating the directory structure, complained it couldn’t and suggested I check if there was enough disk space. There was. The problem was that although I had told DeVeDe that each video was already in DVD format, I had left off the -target ntsc-dvd from the FFMPEG command line for one of the videos. Re-converting it with the proper flag fixed the problem.