maybe this is my problem too since i am on 3.3.1. i just added .f4v of mime type video/mp4 and i am unable to upload.
I also have found that as of 3.3.1 this plugin is non-functional. 🙁 The plugin worked perfectly previous to upgrading to 3.3.1, but now MIME types added via the plugin do not override the ‘file type does not meet security guidelines’ error. 🙁 Any possibility of getting this fixed? 🙂
One other item to note.. it looks like other plugins/themes that add new MIME types are having problems since 3.3.1, too. The forums for the theme Minimatica have a post about it:
http://www.onedesigns.com/support/topic/possible-bug-with-mime-types-in-3-3-1
Perhaps the formatting on the array that WordPress uses to store MIME types has changed?
