Traceback (most recent call last):
  File "/usr/lib/python2.7/runpy.py", line 162, in _run_module_as_main
    "__main__", fname, loader, pkg_name)
  File "/usr/lib/python2.7/runpy.py", line 72, in _run_code
    exec code in run_globals
  File "/usr/bin/youtube-dl/__main__.py", line 7, in <module>
  File "/usr/bin/youtube-dl/__init__.py", line 536, in main

  File "/usr/bin/youtube-dl/__init__.py", line 520, in _real_main

  File "/usr/bin/youtube-dl/FileDownloader.py", line 475, in download
  File "/usr/bin/youtube-dl/InfoExtractors.py", line 80, in extract
  File "/usr/bin/youtube-dl/InfoExtractors.py", line 405, in _real_extract
  File "/usr/bin/youtube-dl/InfoExtractors.py", line 405, in <genexpr>
KeyError: 'sig'