Wordpress and Joomla's flash uploader does not
work with the web server filter we have in place as apache has a bug
that causes the issue in the first place. You'll see the following in
errors in the error_log when trying to upload:
Multipart: final boundary missing
To resolve this, place the following in the .htaccess file for the script:
SetEnvIfNoCase Content-Type "^multipart/form-data;" "MODSEC_NOPOSTBUFFERING=Do not buffer file uploads"