error on gdcvault

[sheepdestroyer]

Error trying to DL : http://gdcvault.com/play/1023644/Augmented-Reality-2-0-Developing

[sheepdestroyer@sheepora ~] $ youtube-dl -v
[debug] System config: []
[debug] User config: []
[debug] Command-line args: [u'-v']
[debug] Encodings: locale UTF-8, fs UTF-8, out UTF-8, pref UTF-8
[debug] youtube-dl version 2016.04.06
[debug] Python version 2.7.10 - Linux-4.4.6-301.fc23.x86_64-x86_64-with-fedora-23-Twenty_Three
[debug] exe versions: ffmpeg 2.8.6, ffprobe 2.8.6, rtmpdump 2.4
[debug] Proxy map: {}
Usage: youtube-dl [OPTIONS] URL [URL...]

youtube-dl: error: You must provide at least one URL.
Type youtube-dl --help to see a list of all options.


[sheepdestroyer@sheepora ~] $ youtube-dl http://gdcvault.com/play/1023644/Augmented-Reality-2-0-Developing
[GDCVault] Augmented-Reality-2-0-Developing: Downloading webpage
WARNING: [GDCVault] It looks like http://www.gdcvault.com/play/1023644 requires a login. Try specifying a username and password and try again.
WARNING: [GDCVault] Could not login.
Traceback (most recent call last):
  File "/usr/lib64/python2.7/runpy.py", line 162, in _run_module_as_main
    "__main__", fname, loader, pkg_name)
  File "/usr/lib64/python2.7/runpy.py", line 72, in _run_code
    exec code in run_globals
  File "/usr/local/bin/youtube-dl/__main__.py", line 19, in <module>
  File "/usr/local/bin/youtube-dl/youtube_dl/__init__.py", line 419, in main
  File "/usr/local/bin/youtube-dl/youtube_dl/__init__.py", line 409, in _real_main
  File "/usr/local/bin/youtube-dl/youtube_dl/YoutubeDL.py", line 1725, in download
  File "/usr/local/bin/youtube-dl/youtube_dl/YoutubeDL.py", line 669, in extract_info
  File "/usr/local/bin/youtube-dl/youtube_dl/extractor/common.py", line 323, in extract
  File "/usr/local/bin/youtube-dl/youtube_dl/extractor/gdcvault.py", line 184, in _real_extract
TypeError: unsupported operand type(s) for +: 'NoneType' and 'unicode'
[sheepdestroyer@sheepora ~] $