Unsafe Mimetypes allows a WordPress admin to decide which file formats can be uploaded to the media library
As Sharlot said: you have to go to Settings>Allowed Mimetypes and enter what you'd like, in my case it was simply swf. Thanks to the plugin author!
Awesome!!!! was needing a m3u radio playlist to upload and this plugin made it happen! thank you kindly for your fine work...
WordPress suddenly didn't allow me to upload swf's anymore. Discovered this plugin and put it to use. Only tried it just now - it's working perfectly. Of course I can't judge whether it has any issues.
One tip: if you try to set the file types, you have to go to Settings>Allowed Mimetypes. The rest is pretty self-explanatory.
Oh, and I'm using the very last WordPress version (3.7.1) though the plugin hasn't been updated for this version. Hope thst won't cause any trouble.