Please add alternate URL for Naver

[BlackHoleSpain]

• I've verified and I assure that I'm running youtube-dl 2016.10.31

• At least skimmed through README and most notably FAQ and BUGS sections

• Searched the bugtracker for similar issues including closed ones

There are several open NAVER issues months ago.

• Site support request (request for adding support for a new site)

NAVER TVCAST site has been working in youtube-dl for years, but it cannot extract data from NAVER MUSIC site. This is an example of a page released a few days ago:

• Single video: http://music.naver.com/artist/videoPlayer.nhn?videoId=68845
• Public example. Not credentials needed or georestriction for that video.

youtube-dl -v http://music.naver.com/artist/videoPlayer.nhn?videoId=68845
[debug] System config: []
[debug] User config: []
[debug] Command-line args: ['-v', 'http://music.naver.com/artist/videoPlayer.nhn?videoId=68845']
[debug] Encodings: locale cp1252, fs mbcs, out cp850, pref cp1252
[debug] youtube-dl version 2016.10.31
[debug] Python version 3.4.4 - Windows-7-6.1.7601-SP1
[debug] exe versions: none
[debug] Proxy map: {}
[generic] videoPlayer: Requesting header
WARNING: Falling back on generic information extractor.
[generic] videoPlayer: Downloading webpage
[generic] videoPlayer: Extracting information
ERROR: Unsupported URL: http://music.naver.com/artist/videoPlayer.nhn?videoId=68845
Traceback (most recent call last):
File "C:\Users\dst\AppData\Roaming\Build archive\youtube-dl\rg3\tmponbili4i\build\youtube_dl\YoutubeDL.py", line 694, in extract_info
File "C:\Users\dst\AppData\Roaming\Build archive\youtube-dl\rg3\tmponbili4i\build\youtube_dl\extractor\common.py", line 356, in extract
File "C:\Users\dst\AppData\Roaming\Build archive\youtube-dl\rg3\tmponbili4i\build\youtube_dl\extractor\generic.py", line 2417, in _real_extract
youtube_dl.utils.UnsupportedError: Unsupported URL: http://music.naver.com/artist/videoPlayer.nhn?videoId=68845

[dstftw]

Duplicate of #5766.