Add support for PRX?

[munkdapp]

Please follow the guide below

Make sure you are using the latest version: run youtube-dl --version and ensure your version is 2018.03.20. If it's not, read this FAQ entry and update. Issues with outdated version will be rejected.

• I've verified and I assure that I'm running youtube-dl 2018.03.20

Before submitting an issue make sure you have:

• At least skimmed through the README, most notably the FAQ and BUGS sections
• Searched the bugtracker for similar issues including closed ones
• Checked that provided video/audio/playlist URLs (if any) are alive and playable in a browser

What is the purpose of your issue?

• Site support request (request for adding support for a new site)

If the purpose of this issue is a site support request please provide all kinds of example URLs support for which should be included (replace following example URLs by yours):

• Single audio track: https://beta.prx.org/stories/234061

Description of your issue, suggested solution and other information

It would be great to be able to download podcasts from PRX, but they don't offer the option and youtube-dl gives me Unsupported URL.

Love the tool, btw. This has changed my life!