I have recently wondered this as well...
I know that LMCE adds extensions to the dvd such as .dvd and I was wondering if that would make a difference when going to burn.... I have not tried it as of yet. I have no problem burning outside the LMCE interface, I just want to make sure I am able to burn something that my dvd player can read.
I would also like to know if there is anything special I need to do to burn files from myth tv to dvd. I have some shows I have recorded that I would like to share with a friend but I have not yet had a chance to try to export those files to dvd.
Any tips or pointers would be helpful.