Error view layout is displayed when sending a featured video of a channel or user to the player

[SoftVision-CarmenFat]

[Affected versions]:

• Firefox 58.0 and up
• Min-Vid Shield Study Onboarding 0.4.7 - Shield Study
• Min Vid v.0.4.8 from Test Pilot

[Affected Platforms]:

• All Windows
• All Mac
• All Linux

[Prerequisites]:

• Latest Min-Vid Shield Study (Onboarding 0.4.7) was previously installed on a clean profile.

[Steps to reproduce]:

1. Open the browser with the profile from prerequisites and navigate to www.youtube.com
2. Click on a user/channel from the homepage (e.g. https://www.youtube.com/user/TheFrasernash).
3. Click on the "Play Now" button from the overlay displayed on the featured video.
4. Observe what happens next.

[Expected result]:

• The video is sent to the player and automatically starts playing.

[Actual result]:

• The error view overlay is displayed.

[Notes]:

• This is also reproducible on the Test Pilot version.
• This is only reproducible with the featured video of the channel/user.
• The video from the screencast below is not embedded since the video can be sent to the player correctly after opening the video in a new tab.
• Attached a screencast of the issue: