Today I Learned

A Hashrocket project

Enable 4k UHD video streaming in Firefox

By default, Firefox does not support the VP9 WebM codec sites like YouTube use to deliver 4k quality video. If you visit a video that supports 4k you won’t even see the option available under the Quality menu.

Test video: https://www.youtube.com/watch?v=Bey4XXJAqS8

To enable it:

  1. visit about:config
  2. search for webm
  3. double click media.mediasource.webm.enabled

demo

And now refresh YouTube result