Renaming of files in python

renameVideoFile

"""
Before filename: recoded_videos%2Falgs4partI-64.mp4 
new_file:        64.mp4 
"""

import os
directory = '<DIR NAME>'
pattern_to_be_excluded = '.mp4'
pattern_to_be_excluded_2 = '-'
k = os.walk(directory) 
files = k.next()[2] #getting the files from generator
for file in files:
  if pattern_to_be_excluded not in file:
      print "not touching file: %s" %(file)
      continue
  if pattern_to_be_excluded_2 not in file:
      print "cannot split the filename: %s" %(file)
      continue  
  new_file = file.split('-')[1]
  print "renaming the file %s with new_file:%s " %(file, new_file)
  os.rename(directory + '/' + file, directory + '/' + new_file)