[TYPO3] Add file extensions to the "Filelinks" content element?

[Bjarne HELLIGSOE]

Hi,

Simple question: Where and how do I add new file extensions to the 
"Filelinks" content element?
On a webpage I am using this element with links to WMV files, and the 
element doesn't not know this file extension, and therefore using the 
default icon. I would like to add the WMV extension.
But how?

Thanks in advanced

Best Regards, Bjarne