i found that changing the name of the .mp4 to .avi works fine. i have encountered no problems yet.
How to change the name from .mp4 to .avi?
I presume he means change the extension (the bit after the 'dot') from .mp4 to .avi on the computer before copying to a key to play on the dvd player. Doubt it will work, I'll give it a try though.