Add vidyard support

[k4rtik]

Please follow the guide below

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

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Make sure you are using the latest version: run youtube-dl --version and ensure your version is 2016.12.01. 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 Issues with outdated version will be rejected.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 2016.12.01

Before submitting an issue make sure you have:

• At least skimmed through README and most notably FAQ and BUGS sections
• Searched the bugtracker for similar issues including closed ones

What is the purpose of your issue?

• Bug report (encountered problems with youtube-dl)
• Site support request (request for adding support for a new site)
• Feature request (request for a new functionality)
• Question
• Other

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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):

Vidyard homepage: https://www.vidyard.com/

• Single video: http://play.vidyard.com/MYsNEfzgpaB4w8xGWL2g7A
• Same video embedded on another site: https://www.purestorage.com/otb/ep1.html
• Downloadable link to the same video: http://cdn.vidyard.com/videos/Tty5gmS1jK8gPPatNZSCRg/full_hd.mp4?5R1bEOiBmTPTd29ZHp6WJbAB2_2Ffz6As5zIVJlFfEBx5r0B6ZGGus0ZpcRiljHOZi7zRLk4BSgvU5-1SIv7pJHEfwz6XHojWyhk0kwVpPMqF94
• Playlist: https://www.youtube.com/playlist?list=PL4lCao7KL_QFVb7Iudeipvc2BCavECqzc

Edit: These all 404 now, see link in the comment below.

[mih-kopylov]

Another video: https://play.vidyard.com/wVn1pCABE7RbkAHm6vNuFu.html

[lofidevops]

Here is an example of an embedded vidyard video:

https://tidelift.com/subscription/webinar/watch/idc/thank-you

Attempted download with version 2020.09.06:

[generic] thank-you: Requesting header
WARNING: Falling back on generic information extractor.
[generic] thank-you: Downloading webpage
[generic] thank-you: Extracting information
ERROR: Unsupported URL: https://tidelift.com/subscription/webinar/watch/idc/thank-you