YouTube player size question

Hi, I am using Firefox with Greasemonkey.

I have installed a userscript which always adds &fmt=18 to YouTube video URLs. But the problem is, whenever the video page loads with fmt 18, the video player size expands by default, meaning that I always have to click the player resize button to make it small again.

My question is, how can I make the player the regular size by default, while still adding &fmt=18 to the URL.

Any help is much appreciated.

My suggestion to solve the problem of a userscript messing up YouTube videos: Remove the userscript.

The userscript is not messing it up, it is just doing what it is supposed to. When you type &fmt=18 to the end of the URL the player goes bigger anyway.