[mediamatters] Add support for mediamatters embeds

[jnbdz]

Please follow the guide below

• You will be asked some questions and requested to provide some information, please read them carefully and answer honestly
• Put an x into all the boxes [ ] relevant to your issue (like that [x])
• Use Preview tab to see how your issue will actually look like

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Make sure you are using the latest version: run youtube-dl --version and ensure your version is 2017.06.05. If it's not read this FAQ entry and update. Issues with outdated version will be rejected.

• I've verified and I assure that I'm running youtube-dl 2017.06.05

Before submitting an issue make sure you have:

• 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)
• Site support request (request for adding support for a new site)
• Feature request (request for a new functionality)
• Question
• Other

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The following sections concretize particular purposed issues, you can erase any section (the contents between triple ---) not applicable to your issue

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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 http://www.theblaze.com/news/2017/06/09/nra-host-calls-out-kim-kardashians-mental-illnesses-over-gun-control-rant/
[debug] System config: []
[debug] User config: []
[debug] Custom config: []
[debug] Command-line args: [u'-v', u'http://www.theblaze.com/news/2017/06/09/nra-host-calls-out-kim-kardashians-mental-illnesses-over-gun-control-rant/']
[debug] Encodings: locale UTF-8, fs UTF-8, out UTF-8, pref UTF-8
[debug] youtube-dl version 2017.06.05
[debug] Python version 2.7.12 - Linux-4.4.0-72-generic-x86_64-with-Ubuntu-16.04-xenial
[debug] exe versions: ffmpeg 2.8.11-0ubuntu0.16.04.1, ffprobe 2.8.11-0ubuntu0.16.04.1
[debug] Proxy map: {}
[generic] nra-host-calls-out-kim-kardashians-mental-illnesses-over-gun-control-rant: Requesting header
WARNING: Falling back on generic information extractor.
[generic] nra-host-calls-out-kim-kardashians-mental-illnesses-over-gun-control-rant: Downloading webpage
[generic] nra-host-calls-out-kim-kardashians-mental-illnesses-over-gun-control-rant: Extracting information
[download] Downloading playlist: None
[generic] playlist None: Collected 2 video ids (downloading 2 of them)
[download] Downloading video 1 of 2
[debug] Invoking downloader on u'http://www.theblaze.com/wp-content/themes/theblaze/audio/new-message.mp3'
[download] Destination: NRA host calls out Kim Kardashian’s ‘mental illnesses’ over gun control rant-nra-host-calls-out-kim-kardashians-mental-illnesses-over-gun-control-rant.mp3
[download] 100% of 32.24KiB in 00:00
[download] Downloading video 2 of 2
[debug] Invoking downloader on u'http://www.theblaze.com/wp-content/themes/theblaze/audio/swoosh.mp3'
[download] NRA host calls out Kim Kardashian’s ‘mental illnesses’ over gun control rant-nra-host-calls-out-kim-kardashians-mental-illnesses-over-gun-control-rant.mp3 has already been downloaded
[download] 100% of 32.24KiB
[download] Finished downloading playlist: None

...
<end of log>

[jnbdz]

Here is another example (this one just fails):

youtube-dl -v https://www.mediamatters.org/blog/2017/06/09/after-comey-s-extremely-damning-testimony-fox-friends-focuses-distractions/216851
[debug] System config: []
[debug] User config: []
[debug] Custom config: []
[debug] Command-line args: [u'-v', u'https://www.mediamatters.org/blog/2017/06/09/after-comey-s-extremely-damning-testimony-fox-friends-focuses-distractions/216851']
[debug] Encodings: locale UTF-8, fs UTF-8, out UTF-8, pref UTF-8
[debug] youtube-dl version 2017.06.05
[debug] Python version 2.7.12 - Linux-4.4.0-72-generic-x86_64-with-Ubuntu-16.04-xenial
[debug] exe versions: ffmpeg 2.8.11-0ubuntu0.16.04.1, ffprobe 2.8.11-0ubuntu0.16.04.1
[debug] Proxy map: {}
[generic] 216851: Requesting header
WARNING: Falling back on generic information extractor.
[generic] 216851: Downloading webpage
[generic] 216851: Extracting information
ERROR: Unsupported URL: https://www.mediamatters.org/blog/2017/06/09/after-comey-s-extremely-damning-testimony-fox-friends-focuses-distractions/216851
Traceback (most recent call last):
  File "/usr/local/bin/youtube-dl/youtube_dl/extractor/generic.py", line 1970, in _real_extract
    doc = compat_etree_fromstring(webpage.encode('utf-8'))
  File "/usr/local/bin/youtube-dl/youtube_dl/compat.py", line 2526, in compat_etree_fromstring
    doc = _XML(text, parser=etree.XMLParser(target=_TreeBuilder(element_factory=_element_factory)))
  File "/usr/local/bin/youtube-dl/youtube_dl/compat.py", line 2515, in _XML
    parser.feed(text)
  File "/usr/lib/python2.7/xml/etree/ElementTree.py", line 1653, in feed
    self._raiseerror(v)
  File "/usr/lib/python2.7/xml/etree/ElementTree.py", line 1517, in _raiseerror
    raise err
ParseError: not well-formed (invalid token): line 51, column 59
Traceback (most recent call last):
  File "/usr/local/bin/youtube-dl/youtube_dl/YoutubeDL.py", line 761, in extract_info
    ie_result = ie.extract(url)
  File "/usr/local/bin/youtube-dl/youtube_dl/extractor/common.py", line 433, in extract
    ie_result = self._real_extract(url)
  File "/usr/local/bin/youtube-dl/youtube_dl/extractor/generic.py", line 2795, in _real_extract
    raise UnsupportedError(url)
UnsupportedError: Unsupported URL: https://www.mediamatters.org/blog/2017/06/09/after-comey-s-extremely-damning-testimony-fox-friends-focuses-distractions/216851