Devede produces unplayable .iso?

Had a few little hitches with the upgrade to 16.04, but nothing major... until now. Was helping my boy make a DVD for his mom for Mother's Day. Used Devede, converted some .mp4 and .mkv files, it produced an ISO image, I bued it.

Then, it wouldn't play on a Playstation 3 or a Playstation 4, or in any DVD playing software. Has anyone else successfully produced a working DVD on 16.04?