code: def skip(self, video_name, out, start, duration):
          
          cfilter = (r"[0:v]trim=duration={start}[av];"
                     r"[0:a]atrim=duration={start}[aa];"
                     r"[0:v]trim=start={offset},setpts=PTS-STARTPTS[bv];"
                     r"[0:a]atrim=start={offset},asetpts=PTS-STARTPTS[ba];"
                     r"[av][bv]concat[outv];[aa][ba]concat=v=0:a=1[outa]")\
              .format(start=start, offset=start + duration)\
              .replace(' ', '')
  
          command = ['ffmpeg', '-i', video_name,
              '-filter_complex', cfilter, '-y',
              '-map', '[outv]',
              '-map', '[outa]', '-c:v', 'huffyuv', '-preset', 'veryslow',
              out]
  
          if self.verbose:
              print 'Skipping {0} into {1}'.format(video_name, out)
              print ' '.join(command)
  
          call(command)
docs: Skips a section of the clip
          @param video_name : name of video input file
          @param out : name of output file
          @param start : start time of the skip (seconds)
          @param duration : duration of the skip (seconds)