This may be true for CDs (dunno, haven't played a CD in my Edge yet), but I've personally never been able to get FF to work when playing from a flash drive over USB. If one has to press and hold a while, it must need to be a loooong while...
I think this might be a bug, and would certainly like FF to work. Even better, if FF could be made to work by pressing on the progress bar, that would be way nice.
--Rick