TypeError exception on GDC Vault 2016 free videos

[snarfed]

thanks in advance!...

• I've verified and I assure that I'm running youtube-dl 2016.04.06
• At least skimmed through README and most notably FAQ and BUGS sections
• Searched the bugtracker for similar issues including closed ones

What is the purpose of your issue?

• Bug report (encountered problems with youtube-dl)

If the purpose of this issue is a bug report, site support request or you are not completely sure provide the full verbose output as follows:

Add -v flag to your command line you run youtube-dl with, copy the whole output and insert it here. It should look similar to one below (replace it with your log inserted between triple ```):

$ youtube-dl -v -C http://gdcvault.com/play/1023657/Escaping-the-Holodeck-Storytelling-and
[debug] System config: []
[debug] User config: []
[debug] Command-line args: [u'-v', u'-C', u'http://gdcvault.com/play/1023657/Escaping-the-Holodeck-Storytelling-and']
[debug] Encodings: locale US-ASCII, fs utf-8, out US-ASCII, pref US-ASCII
[debug] youtube-dl version 2016.04.06
[debug] Python version 2.7.10 - Darwin-15.4.0-x86_64-i386-64bit
[debug] exe versions: ffmpeg 2.8.6, ffprobe 2.8.6
[debug] Proxy map: {}
[debug] Public IP address: 67.169.95.105
[GDCVault] Escaping-the-Holodeck-Storytelling-and: Downloading webpage
WARNING: [GDCVault] It looks like http://www.gdcvault.com/play/1023657 requires a login. Try specifying a username and password and try again.
WARNING: [GDCVault] Could not login.
Traceback (most recent call last):
  File "/Users/ryan/local/bin/youtube-dl", line 11, in <module>
    sys.exit(main())
  File "/Users/ryan/local/lib/python2.7/site-packages/youtube_dl/__init__.py", line 419, in main
    _real_main(argv)
  File "/Users/ryan/local/lib/python2.7/site-packages/youtube_dl/__init__.py", line 409, in _real_main
    retcode = ydl.download(all_urls)
  File "/Users/ryan/local/lib/python2.7/site-packages/youtube_dl/YoutubeDL.py", line 1725, in download
    url, force_generic_extractor=self.params.get('force_generic_extractor', False))
  File "/Users/ryan/local/lib/python2.7/site-packages/youtube_dl/YoutubeDL.py", line 669, in extract_info
    ie_result = ie.extract(url)
  File "/Users/ryan/local/lib/python2.7/site-packages/youtube_dl/extractor/common.py", line 323, in extract
    return self._real_extract(url)
  File "/Users/ryan/local/lib/python2.7/site-packages/youtube_dl/extractor/gdcvault.py", line 184, in _real_extract
    xml_description_url = xml_root + 'xml/' + xml_name
TypeError: unsupported operand type(s) for +: 'NoneType' and 'unicode'

Description of your issue, suggested solution and other information

youtube-dl raises an exception when trying to download free 2016 GDC Vault videos like http://gdcvault.com/play/1023657/Escaping-the-Holodeck-Storytelling-and . evidently xml_root at extractor/gdcvault.py:184 is assumed to be a string, but in this case is None.

the earlier log messages about needing a login are also suspicious, but may not be related.

the couple other currently open GDC Vault issues (#2673, #4170) are different bugs.

thanks in advance!

[jaimeMF]

Fixed with 3c6c7e7, it will be available in the next release. But thanks for reporting the issue!