code: public MovieBox getMovieBox() {
          for (Box box : getBoxes()) {
              if (box instanceof MovieBox) {
                  return (MovieBox) box;
              }
          }
          return null;
      }
docs: Shortcut to get the MovieBox since it is often needed and present in
  nearly all ISO 14496 files (at least if they are derived from MP4 ).
  
  @return the MovieBox or <code>null</code>