Before wasting any more disks, try playing the output from DVDFlick on the computer. If you don’t have software for playing dvd-video, try a free media player called VLC. www.videolan.org
Another way to test the output is to use DVDShrink. Just try to open the files with DVDShrink and see if it can analyze them. DVDShrink is a stickler for exact dvd specifications in the input, so if it cannot open the file, you know something has gone awry in the encoding.
Recommending a new burner…hmmm. One good IDE/PATA interface drive that may still be available is the Optiarc 7200a (NOT the 7220 series!!). Another possibility would be the Pioneer 117.
If you can use a SATA interface drive, the new Optiarc 7240s is pretty good.