UserAgent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/68.0.3440.106 Safari/537.36

Example URL:
https://www.youtube.com/watch?v=1yATFrNUAFw

Steps to reproduce the problem:
1. Enable servicified service workers (chrome://flags/#enable-service-worker-servicification), disable out of blink CORS (chrome://flags/#out-of-blink-cors) and restart the browser.
2. Try to play some YouTube videos.

What is the expected behavior?
YouTube videos play normally.

What went wrong?
YouTube videos fail to play.  JavaScript console shows errors about failing to load resources from googlevideo.com due to "No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'https://www.youtube.com' is therefore not allowed access."

Did this work before? N/A 

Chrome version: 68.0.3440.106  Channel: stable
OS Version: Fedora 28
Flash Version: 

Everything works fine if out of blink CORS is also enabled.

Videos can be temporarily made to play by using the console to remove all YouTube services workers and then reloading a YouTube page, but the problem comes back when attempting to view any further videos.

This is a refiling of  issue 870478  with better information.