Repository: youtube-dl
Issue: Add support: SBTV.com (local news livestreams)
Labels: site-support-request

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## Checklist

<!--
Carefully read and work through this check list in order to prevent the most common mistakes and misuse of youtube-dl:
- First of, make sure you are using the latest version of youtube-dl. Run `youtube-dl --version` and ensure your version is 2020.06.16.1. If it's not, see https://yt-dl.org/update on how to update. Issues with outdated version will be REJECTED.
- Make sure that all provided video/audio/playlist URLs (if any) are alive and playable in a browser.
- Make sure that site you are requesting is not dedicated to copyright infringement, see https://yt-dl.org/copyright-infringement. youtube-dl does not support such sites. In order for site support request to be accepted all provided example URLs should not violate any copyrights.
- Search the bugtracker for similar site support requests: http://yt-dl.org/search-issues. DO NOT post duplicates.
- Finally, put x into all relevant boxes (like this [x])
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- [x] I'm reporting a new site support request
- [x] I've verified that I'm running youtube-dl version **2020.06.16.1**
- [x] I've checked that all provided URLs are alive and playable in a browser
- [x] I've checked that none of provided URLs violate any copyrights
- [x] I've searched the bugtracker for similar site support requests including closed ones


## Example URLs

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Provide all kinds of example URLs support for which should be included. Replace following example URLs by yours.
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- Single video: https://www.sbtv.com/live/11937/wfmz
## Description

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Please consider adding support for SBTV.com, which hosts many free live streams for American local news affiliates. No credentials are needed. 

youtube-dl --verbose 'https://www.sbtv.com/live/11937/wfmz'
[debug] System config: []
[debug] User config: []
[debug] Custom config: []
[debug] Command-line args: [u'--verbose', u'https://www.sbtv.com/live/11937/wfmz']
[debug] Encodings: locale UTF-8, fs utf-8, out UTF-8, pref UTF-8
[debug] youtube-dl version 2020.06.16.1
[debug] Python version 2.7.16 (CPython) - Darwin-19.5.0-x86_64-i386-64bit
[debug] exe versions: ffmpeg 4.3, ffprobe 4.3, rtmpdump 2.4
[debug] Proxy map: {}
[generic] wfmz: Requesting header
WARNING: Falling back on generic information extractor.
[generic] wfmz: Downloading webpage
[generic] wfmz: Extracting information
ERROR: Unsupported URL: https://www.sbtv.com/live/11937/wfmz
Traceback (most recent call last):
  File "/usr/local/bin/youtube-dl/youtube_dl/extractor/generic.py", line 2387, in _real_extract
    doc = compat_etree_fromstring(webpage.encode('utf-8'))
  File "/usr/local/bin/youtube-dl/youtube_dl/compat.py", line 2562, 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 2551, in _XML
    parser.feed(text)
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/xml/etree/ElementTree.py", line 1659, in feed
    self._raiseerror(v)
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/xml/etree/ElementTree.py", line 1523, in _raiseerror
    raise err
ParseError: not well-formed (invalid token): line 6, column 30
Traceback (most recent call last):
  File "/usr/local/bin/youtube-dl/youtube_dl/YoutubeDL.py", line 797, in extract_info
    ie_result = ie.extract(url)
  File "/usr/local/bin/youtube-dl/youtube_dl/extractor/common.py", line 530, in extract
    ie_result = self._real_extract(url)
  File "/usr/local/bin/youtube-dl/youtube_dl/extractor/generic.py", line 3382, in _real_extract
    raise UnsupportedError(url)
UnsupportedError: Unsupported URL: https://www.sbtv.com/live/11937/wfmz