Choral Public Domain Library

I uploaded a mp4 "karaoke video" for Hugo Distler, "Lobe den Herren" http://www.cpdl.org/wiki/index.php/Lobe_den_Herren_%28Hugo_Distler%29 . The upload dialogue allows .mp4 files, but they are declared to be "unwanted". I believe that such files are usefull, but what do...