If when trying to open a movie with QuickTime, you end up with this message "-2041 error an invalid sample description was found in the movie" but you have the K-lite codec pack and the same video can play with VLC or media player classic but with no audio ……
then all you have 2 do is to RENAME the file to .3gp
Right now I renamed a .m4v file -which wasn’t playing on my external box- to .mpg and it plays fine !!