Repository: youtube-dl
Issue: Authenticated GDC Vault 2019 content throws exception
Labels: account-needed

---
- [x] I've **verified** and **I assure** that I'm running youtube-dl **2019.04.07**
- [x] At least skimmed through the [README](https://github.com/ytdl-org/youtube-dl/blob/master/README.md)
- [x] [Searched](https://github.com/ytdl-org/youtube-dl/search?type=Issues) the bugtracker for similar issues including closed ones
- [x] Checked that provided video/audio/playlist URLs (if any) are alive and playable in a browser

### What is the purpose of your *issue*?
- [x] Bug report (encountered problems with youtube-dl)
- [ ] Site support request (request for adding support for a new site)
- [ ] Feature request (request for a new functionality)
- [ ] Question
- [ ] Other

---
### ERROR: Authentical Failure / Redirect
#### "Unsupported URL: https://www.gdcvault.com/login"

I'm able to access the requisite content in a web browser, but youtube-dl appears to fail when authenticating due to a login redirect (?)

As there appear to be known issues with the GDCVault extractor (2019), I'm using the generic extractor as advised in other reports.

#### Log Output: Failure

```
[debug] System config: []
[debug] User config: []
[debug] Custom config: []
[debug] Command-line args: [u'--force-generic-extractor', u'--username', u'PRIVATE', u'--password', u'PRIVATE', u'--verbose', u'https://www.gdcvault.com/play/1025986/Creating-a-Deeper-Emotional-Connection']
[debug] Encodings: locale cp1252, fs mbcs, out cp850, pref cp1252
[debug] youtube-dl version 2019.04.07
[debug] Python version 2.7.15 (CPython) - Windows-10-10.0.17763
[debug] exe versions: none
[debug] Proxy map: {}
[generic] Creating-a-Deeper-Emotional-Connection: Requesting header
[redirect] Following redirect to https://www.gdcvault.com/login
[generic] login: Requesting header
WARNING: Forcing on generic information extractor.
[generic] login: Downloading webpage
[generic] login: Extracting information
ERROR: Unsupported URL: https://www.gdcvault.com/login
Traceback (most recent call last):
  File "c:\python27\lib\site-packages\youtube_dl\extractor\generic.py", line 2337, in _real_extract
    doc = compat_etree_fromstring(webpage.encode('utf-8'))
  File "c:\python27\lib\site-packages\youtube_dl\compat.py", line 2551, in compat_etree_fromstring
    doc = _XML(text, parser=etree.XMLParser(target=_TreeBuilder(element_factory=_element_factory)))
  File "c:\python27\lib\site-packages\youtube_dl\compat.py", line 2540, in _XML
    parser.feed(text)
  File "c:\python27\lib\xml\etree\ElementTree.py", line 1659, in feed
    self._raiseerror(v)
  File "c:\python27\lib\xml\etree\ElementTree.py", line 1523, in _raiseerror
    raise err
ParseError: not well-formed (invalid token): line 51, column 22
Traceback (most recent call last):
  File "c:\python27\lib\site-packages\youtube_dl\YoutubeDL.py", line 796, in extract_info
    ie_result = ie.extract(url)
  File "c:\python27\lib\site-packages\youtube_dl\extractor\common.py", line 529, in extract
    ie_result = self._real_extract(url)
  File "c:\python27\lib\site-packages\youtube_dl\extractor\generic.py", line 3320, in _real_extract
    raise UnsupportedError(url)
UnsupportedError: Unsupported URL: https://www.gdcvault.com/login
```

As a control case, in contrast here is an example of output that works; the only difference in the passed arguments is the target URL.  Unlike the above failure, the content at the below URL does not require authentication, subsequently youtube-dl is successful

#### Example Log Output: Success

```
[debug] System config: []
[debug] User config: []
[debug] Custom config: []
[debug] Command-line args: [u'--force-generic-extractor', u'--username', u'PRIVATE', u'--password', u'PRIVATE', u'--verbose', u'https://www.gdcvault.com/play/1026496/-Marvel-s-Spider-Man']
[debug] Encodings: locale cp1252, fs mbcs, out cp850, pref cp1252
[debug] youtube-dl version 2019.04.07
[debug] Python version 2.7.15 (CPython) - Windows-10-10.0.17763
[debug] exe versions: none
[debug] Proxy map: {}
[generic] -Marvel-s-Spider-Man: Requesting header
WARNING: Forcing on generic information extractor.
[generic] -Marvel-s-Spider-Man: Downloading webpage
[generic] -Marvel-s-Spider-Man: Extracting information
[Kaltura] 1_bln945rf: Downloading video info JSON
[Kaltura] 1_bln945rf: Downloading m3u8 information
[debug] Default format spec: best/bestvideo+bestaudio
[debug] Invoking downloader on u'http://cdnapi.kaltura.com/p/1670711/sp/167071100/playManifest/entryId/1_bln945rf/format/url/protocol/http/flavorId/1_tl9ywps0?referrer=aHR0cHM6Ly93d3cuZ2RjdmF1bHQuY29t'
[download] Destination: Marvel's Spider-Man' - A Technical Postmortem-1_bln945rf.mp4
[download] 100% of 1.61GiB in 00:27
```

### Final Note: Failure Testing

A possible clue:  note that when I attempt to provide bogus credentials, I get identical output as in the above two cases -- free content works, but secure content fails with the same URL error, perhaps indicating that authentication is altogether non-functional as it appears to make no difference

*Note that I do have valid credentials, which work as expected when entering them directly onto the website and viewing content in the embedded player*

---