Repository: youtube-dl
Issue: [FrontendMasters.com] Course download is broken
Labels: account-needed

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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 2019.05.20. 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 Issues with outdated version will be REJECTED.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 all URLs and arguments with special characters are properly quoted or escaped as explained in http://yt-dl.org/escape.
- Search the bugtracker for similar issues: 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 broken site support
- [x] I've verified that I'm running youtube-dl version **2019.05.20**
- [x] I've checked that all provided URLs are alive and playable in a browser
- [x] I've checked that all URLs and arguments with special characters are properly quoted or escaped
- [x] I've searched the bugtracker for similar issues including closed ones


## Verbose log

<!--
Provide the complete verbose output of youtube-dl that clearly demonstrates the problem.
Add the `-v` flag to your command line you run youtube-dl with (`youtube-dl -v <your command line>`), copy the WHOLE output and insert it below. It should look similar to this:
 [debug] System config: []
 [debug] User config: []
 [debug] Command-line args: [u'-v', u'http://www.youtube.com/watch?v=BaW_jenozKcj']
 [debug] Encodings: locale cp1251, fs mbcs, out cp866, pref cp1251
 [debug] youtube-dl version 2019.05.20
 [debug] Python version 2.7.11 - Windows-2003Server-5.2.3790-SP2
 [debug] exe versions: ffmpeg N-75573-g1d0487f, ffprobe N-75573-g1d0487f, rtmpdump 2.4
 [debug] Proxy map: {}
 <more lines>
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```
[debug] System config: []
[debug] User config: []
[debug] Custom config: []
[debug] Command-line args: ['-v', '-u', 'PRIVATE', '-p', 'PRIVATE', 'https://frontendmasters.com/courses/api-design-nodejs-v3']
[debug] Encodings: locale UTF-8, fs utf-8, out UTF-8, pref UTF-8
[debug] youtube-dl version 2019.05.20
[debug] Python version 3.7.3 (CPython) - Darwin-18.2.0-x86_64-i386-64bit
[debug] exe versions: ffmpeg 4.1.3, ffprobe 4.1.3, rtmpdump 2.4
[debug] Proxy map: {}
[FrontendMastersCourse] Downloading login page
[FrontendMastersCourse] Logging in
[FrontendMastersCourse] api-design-nodejs-v3: Downloading course JSON
[download] Downloading playlist: API Design in Node.js, v3
[FrontendMastersCourse] playlist API Design in Node.js, v3: Collected 43 video ids (downloading 43 of them)
[download] Downloading video 1 of 43
[FrontendMasters] Downloading login page
[FrontendMasters] Logging in
[FrontendMasters] FCTNhDyqII: Downloading webm-low source JSON
WARNING: Unable to download JSON metadata: HTTP Error 403: Forbidden
Traceback (most recent call last):
  File "/usr/local/Cellar/python/3.7.3/Frameworks/Python.framework/Versions/3.7/lib/python3.7/runpy.py", line 193, in _run_module_as_main
    "__main__", mod_spec)
  File "/usr/local/Cellar/python/3.7.3/Frameworks/Python.framework/Versions/3.7/lib/python3.7/runpy.py", line 85, in _run_code
    exec(code, run_globals)
  File "/usr/local/bin/youtube-dl/__main__.py", line 19, in <module>
  File "/usr/local/bin/youtube-dl/youtube_dl/__init__.py", line 474, in main
  File "/usr/local/bin/youtube-dl/youtube_dl/__init__.py", line 464, in _real_main
  File "/usr/local/bin/youtube-dl/youtube_dl/YoutubeDL.py", line 2008, in download
  File "/usr/local/bin/youtube-dl/youtube_dl/YoutubeDL.py", line 807, in extract_info
  File "/usr/local/bin/youtube-dl/youtube_dl/YoutubeDL.py", line 1006, in process_ie_result
  File "/usr/local/bin/youtube-dl/youtube_dl/YoutubeDL.py", line 873, in process_ie_result
  File "/usr/local/bin/youtube-dl/youtube_dl/YoutubeDL.py", line 796, in extract_info
  File "/usr/local/bin/youtube-dl/youtube_dl/extractor/common.py", line 529, in extract
  File "/usr/local/bin/youtube-dl/youtube_dl/extractor/frontendmasters.py", line 161, in _real_extract
TypeError: 'bool' object is not subscriptable
```


## Description

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I tried with all these links, but none worked:
- https://frontendmasters.com/courses/api-design-nodejs-v3
- https://frontendmasters.com/courses/graphql
- https://frontendmasters.com/courses/electron-v2
- https://frontendmasters.com/courses/firebase-react-v2
- https://frontendmasters.com/courses/typescript-v2
- https://frontendmasters.com/courses/deep-javascript-v3
- https://frontendmasters.com/courses/js-recent-parts
- https://frontendmasters.com/courses/python
- https://frontendmasters.com/courses/intermediate-python