Fix #93 YoutubePlaylistsIE

[ZenulAbidin]

Please follow the guide below

• You will be asked some questions, please read them carefully and answer honestly
• Put an x into all the boxes [ ] relevant to your pull request (like that [x])
• Use Preview tab to see how your pull request will actually look like

---

Before submitting a pull request make sure you have:

• At least skimmed through adding new extractor tutorial and youtube-dl coding conventions sections
• Searched the bugtracker for similar pull requests
• Checked the code with flake8

In order to be accepted and merged into youtube-dl each piece of code must be in public domain or released under Unlicense. Check one of the following options:

• I am the original author of this code and I am willing to release it under Unlicense
• I am not the original author of this code but it is in public domain or released under Unlicense (provide reliable evidence)

What is the purpose of your pull request?

• Bug fix
• Improvement
• New extractor
• New feature

---

Description of your pull request and other information

Changes the regular expressions in YoutubePlaylistsIE to accommodate the new JSON endpoint, fixing a bug where downloading a user's entire set of playlists no longer works.

[someziggyman]

Though this would fix the recent problem listed here
#148

But unfortunately it did not. These could however be not related.

[ZenulAbidin]

Though this would fix the recent problem listed here
#148

But unfortunately it did not. These could however be not related.

This PR only fixes the playlists in the channel, not the videos. I’d need to make a separate fix for that.

[insaneracist]

this seems good 👍