Videomaker – Learn video production and editing, camera reviews › Forums › Technique › Sound › ENCORE DVD MOTION MENUS/BUTTONS
you need to make sure the motion menus (video background) are m2v format
from premiere select mpeg 2 dvd and on your multiplexer set to none.
this is how I create all video to be used as motion backgrounds in Encore.
Encore is notorious for having random undefined footage handling errors. Try transcoding your sources before linking them to the button.