Automatic subtitle list/download not working

[AndrewJDR]

It doesn't seem like automatic captions are being downloaded, even though when I go to the video in Chrome, the "CC" option is available, and it shows as an Auto Generated subtitle at the top of the video when I turn it on.

The video in question:
https://www.youtube.com/watch?v=20LmZk1hakA
Listing subs fails to find auto captions:

youtube-dl -v --list-sub --skip-download https://www.youtube.com/watch?v=20LmZk1hakA

[debug] System config: []
[debug] User config: []
[debug] Command-line args: [u'-v', u'--list-sub', u'--skip-download', u'https://www.youtube.com/watch?v=20LmZk1hakA']
[debug] Encodings: locale UTF-8, fs UTF-8, out UTF-8, pref UTF-8
[debug] youtube-dl version 2016.02.22
[debug] Python version 2.7.6 - Linux-4.2.0-30-generic-x86_64-with-LinuxMint-17.3-rosa
[debug] exe versions: avconv 9.18-6, avprobe 9.18-6
[debug] Proxy map: {}
[youtube] 20LmZk1hakA: Downloading webpage
[youtube] 20LmZk1hakA: Downloading video info webpage
[youtube] 20LmZk1hakA: Extracting video information
WARNING: video doesn't have subtitles
[youtube] 20LmZk1hakA: Looking for automatic captions
WARNING: Couldn't find automatic captions for 20LmZk1hakA
[youtube] 20LmZk1hakA: Downloading MPD manifest
20LmZk1hakA has no automatic captions
20LmZk1hakA has no subtitles

Also fails to download them:

youtube-dl -v --skip-download --write-sub --write-auto-sub --sub-lang "en" https://www.youtube.com/watch?v=20LmZk1hakA

[debug] System config: []
[debug] User config: []
[debug] Command-line args: [u'-v', u'--skip-download', u'--write-sub', u'--write-auto-sub', u'--sub-lang', u'en', u'https://www.youtube.com/watch?v=20LmZk1hakA']
[debug] Encodings: locale UTF-8, fs UTF-8, out UTF-8, pref UTF-8
[debug] youtube-dl version 2016.02.22
[debug] Python version 2.7.6 - Linux-4.2.0-30-generic-x86_64-with-LinuxMint-17.3-rosa
[debug] exe versions: avconv 9.18-6, avprobe 9.18-6
[debug] Proxy map: {}
[youtube] 20LmZk1hakA: Downloading webpage
[youtube] 20LmZk1hakA: Downloading video info webpage
[youtube] 20LmZk1hakA: Extracting video information
WARNING: video doesn't have subtitles
[youtube] 20LmZk1hakA: Looking for automatic captions
WARNING: Couldn't find automatic captions for 20LmZk1hakA
[youtube] 20LmZk1hakA: Downloading MPD manifest
WARNING: Your copy of avconv is outdated and unable to properly mux separate video and audio files, youtube-dl will download single file media. Update avconv to version 10-0 or newer to fix this.