Peter Westwood

This plugin allows you to configure extra mime-types for support by the inline-uploader.
A new options page is added as Options … Mime-types which allows you to add/delete the extra mime-types.
By default the following extra mime-types are registered: audio/ac3, audio/MPA and video/x-flv.
With version 0.90 of the plugin you are now able to upload a file containing a long list of mime types as an easy way to register multiple mime-types. 
The file format is “mime/type extension” for example like this:
<pre><code>audio/ac3 ac3
audio/MPA mpa
video/x-flv flv
</code></pre>

PJW Mime Config

This plugin allows you to configure extra mime-types for support by the inline-uploader.

Sebastian Krysmanski

By default, WordPress only allows a very limited set of file types to be uploaded. This set is defined by a so called 
“white list”. What’s not on the white list can’t be uploaded.
This plugin allows you to extend this white list through a settings page.
Additionally it comes with a wide range of file types that are enabled automatically, like audio files (ac3, mp4, …) 
and video files (avi, mkv, …).

Upload File Type Settings Plugin

This plugin allows admins to specify additional file types that are allowed for uploading to…

PJW Mime Config vs Upload File Type Settings Plugin