I hope this is the same as the "My DVD" software that came with my Toast 14 yesterday.
I took some AVCHD files, used Toast 14 to make them NTSC .movs (29.97, 640x480 about as generic as Toast can do).
Dropped a .mov into MyDVD, and got the "Unacceptable File Type" error.
Useless, because the warning box doesn't say "why"!!
What do you guys do?