Disable Fullscreen Video Transition Delay in Firefox

This article provides a quick guide on how to eliminate the default fade-to-black animation delay when entering and exiting fullscreen HTML5 videos in the Mozilla Firefox web browser. By accessing Firefox's advanced configuration settings and modifying the full-screen-api.transition-duration preferences, you can make fullscreen transitions happen instantaneously.

To remove the fullscreen transition delay, follow these steps:

1. Open the Configuration Editor: Open a new tab in Firefox, type about:config into the address bar, and press Enter.
2. Accept the Warning: You may see a warning page stating "Proceed with Caution." Click the Accept the Risk and Continue button to access the settings.
3. Locate the Transition Settings: In the "Search preference name" box at the top of the page, type or paste the following: full-screen-api.transition-duration
4. Modify the Enter Transition: Locate the preference named full-screen-api.transition-duration.enter. Double-click on it (or click the pencil icon on the right) to edit its value. Change the value from 200 200 to 0 0 and press Enter (or click the checkmark) to save it.
5. Modify the Leave Transition: Locate the preference named full-screen-api.transition-duration.leave. Double-click on it to edit its value. Change the value from 200 200 to 0 0 and press Enter to save it.

The changes take effect immediately without needing to restart the browser. When you enter or exit fullscreen mode on any HTML5 video player, such as YouTube, the transition will now be instant without any fade-to-black delay. To revert this change in the future, simply return to the same settings and click the reset arrow on the far right of both preferences to restore the default 200 200 values.