When running your script this morning I found that over half of the songs in the playlist I loaded were erroring out with this:
ERROR: Signature extraction failed: Traceback (most recent call last): File "C:\Program Files (x86)\Python27\lib\site-packages\youtube_dl\extractor\youtube.py", line 1011, in _decrypt_signature video_id, player_url, s File "C:\Program Files (x86)\Python27\lib\site-packages\youtube_dl\extractor\youtube.py", line 925, in _extract_signature_function errnote='Download of %s failed' % player_url) File "C:\Program Files (x86)\Python27\lib\site-packages\youtube_dl\extractor\common.py", line 519, in _download_webpage res = self._download_webpage_handle(url_or_request, video_id, note, errnote, fatal, encoding=encoding, data=data, headers=headers, query=query) File "C:\Program Files (x86)\Python27\lib\site-packages\youtube_dl\extractor\common.py", line 426, in _download_webpage_handle urlh = self._request_webpage(url_or_request, video_id, note, errnote, fatal, data=data, headers=headers, query=query) File "C:\Program Files (x86)\Python27\lib\site-packages\youtube_dl\extractor\common.py", line 406, in _request_webpage return self._downloader.urlopen(url_or_request) File "C:\Program Files (x86)\Python27\lib\site-packages\youtube_dl\YoutubeDL.py", line 2001, in urlopen return self._opener.open(req, timeout=self._socket_timeout) File "C:\Program Files (x86)\Python27\lib\urllib2.py", line 421, in open protocol = req.get_type() File "C:\Program Files (x86)\Python27\lib\urllib2.py", line 283, in get_type raise ValueError, "unknown url type: %s" % self.__original ValueError: unknown url type: /yts/jsbin/player-en_US-vflp0EuAP/base.js (caused by ValueError(u'unknown url type: /yts/jsbin/player-en_US-vflp0EuAP/base.js',)); please report this issue on https://yt-dl.org/bug . Make sure you are using the latest version; see https://yt-dl.org/update on how to update. Be sure to call youtube-dl with the --verbose flag and include its complete output. Failed to download song. Will retry after other songs.
Following the breadcrumbs I found the youtube-dl repo, downloaded the master, and overwrote those files into Python27\lib\site-packages\youtube_dl\ . Ran the script again and all the songs worked.
Youtube-DL Master
If anyone else is having this issue, you just need to update youtube-dl in the Python install folder.