Uploaded August 2008 | Updated September 2026, 12 hours ago

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This will only work in FireFox!
mozilla.com/en-US/firefox

Get GreaseMonkey:
addons.mozilla.org/en-US/firefox/addon/748 (It added a space... remove it and the link will work)

Goto "Tools - GreaseMonkey - New User Script..."

Name and description can be whatever you want, none of these settings are important yet.

Add this to the newly created file...

IMPORTANT! IT ADDED A SPACE AFTER &fmt= SO IT LOOKS LIKE &fmt= 18! REMOVE THE SPACE OR THIS WILL NOT WORK!


if (window.location.toString().match("&fmt=18") == null) {
window.location.replace(window.location + '&fmt=18');
}

Goto "Tools - GreaseMonkey - Manage User Scripts..."

Select the script you just created.

Under "Included Pages" delete whatever is already there, and add these two links:
youtube.com/watch?v=*
youtube.com/watch?v=*

You're finished! :D