在我的 12.04 LTS 上，我无法通过 youtube-dl 从 YouTube 下载。我曾经这样做过，但最近（一周）我不能。我尝试了很多视频，但得到了相同的输出：
$ youtube-dl -t http://www.youtube.com/watch?v=Sh0ciyuXbJA
[youtube] Setting language
[youtube] Sh0ciyuXbJA: Downloading video webpage
[youtube] Sh0ciyuXbJA: Downloading video info webpage
[youtube] Sh0ciyuXbJA: Extracting video information
Traceback (most recent call last):
File "/usr/bin/youtube-dl", line 4645, in <module>
main()
File "/usr/bin/youtube-dl", line 4636, in main
_real_main()
File "/usr/bin/youtube-dl", line 4620, in _real_main
retcode = fd.download(all_urls)
File "/usr/bin/youtube-dl", line 869, in download
ie.extract(url)
File "/usr/bin/youtube-dl", line 1135, in extract
return self._real_extract(url)
File "/usr/bin/youtube-dl", line 1406, in _real_extract …