Create contribution: Cannot add youtube playlist

[roschaefer]

Describe the bug
When I add a youtube playlist link to a message, the link is replaced with a youtube embed item but the link brings me to an unavailable video.

To Reproduce
Steps to reproduce the behavior:

1. Go to the index page
2. Click on the plus icon to create a post
3. Scroll down to the editor
4. Type in the following link: https://www.youtube.com/watch?v=KghTqdM6FdI&list=PL1CiawkXA01OZyC-MEKAhw7cLA7mD6_tG
5. Click on embedded youtube video item
6. End up here: https://www.youtube.com/watch?v=PL1CiawkXA0 (Video unavailable)

Expected behavior
I would expect the link not to be masked or changed in any way.

Screenshots

Desktop (please complete the following information):

• OS: Linux (Arch)
• Browser: Chromium
• Version 69.0.3497.81

[appinteractive]

This has to be addressed in the Embed-API repository as there happens the whole processing. The issue is that we output the processed link (clean version used for detecting embed type) instead of the original one.

But still we need to respect the time and playlist parameters while fetching the preview image.

[appinteractive]

related with #64