Support for WordPress Multisite

This plugin doesn’t work with WordPress Multisite because the ‘uploads’ section is hidden.

I have modified it to work – the modified version of amfe.php can be found here: https://gist.github.com/4257872

The changes are in add_media_field(), plus the new function display_ext_section().

http://wordpress.org/extend/plugins/add-more-files-extensions/