code: def durationSeconds(self):
          
          f=0.0
          if self.isVideo() or self.isAudio():
              if self.__dict__['duration']:
                  try:
                      f=float(self.__dict__['duration'])
                  except Exception as e:
                      print "None numeric duration"
          return f
docs: Returns the runtime duration of the video stream as a floating point number of seconds.
          Returns 0.0 if not a video stream.