Try this out! If you are using nokia-java . . Try renaming your folder . .with (.otb or .nth) example-my music.otb or my picture.nth
*note- don't try on x2 .

but when hidden video file[3gp,mp4 etc] they still exist in videoplayer wish u provide a default play. Make a playlist in different folder for file u hide,dont simply click on file u wanna view or play,just load a playlist.it will more private,in case your phone had another user. If the user expert they will manage to find out where u hide the file, simply put a security code into fexplorer or explore.

Ya they just pop up in video player so, better change the short cut of the music or video player or either you can put a security unto your player :-)