Sergey Biryukov

Recent minor updates for WordPress introduced a couple of regressions when uploading audio and video files:
<ul>
<li>
On WordPress 4.3.x and earlier branches, audio/video files cannot be uploaded at all due to a fatal error.
Full list of affected versions: 3.7.19, 3.8.19, 3.9.17, 4.0.16, 4.1.16, 4.2.13, 4.3.9.
This will be fixed in the next minor update, see the <a href="https://core.trac.wordpress.org/ticket/40085" rel="nofollow ugc">Trac ticket #40085</a>.
</li>
<li>
On WordPress 4.4.x and later branches, audio/video files are uploaded with corrupted thumbnails.
Full list of affected versions: 4.4.8, 4.5.7, 4.6.4, 4.7.3.
This will be fixed in the next minor update, see the <a href="https://core.trac.wordpress.org/ticket/40075" rel="nofollow ugc">Trac ticket #40075</a>.
</li>
</ul>
In the meantime, this plugin is a workaround that solves both issues and restores the upload functionality for audio and video files.
Don’t forget to remove the plugin once the next minor WordPress update is available!

Correct Audio/Video Uploads

Restores the ability to upload audio & video files in recent minor WordPress updates.

Sybre Waaijer

Pro Mime Types adds a nifty (network) admin interface for allowing or blocking many file extensions for uploading media, documents, and other attachments.
It also shows you a list of all allowed MIME types on the site or network.
<ul>
<li>When a MIME type is allowed, users who can upload files can now do so for that MIME type.</li>
<li>When a MIME type is blocked, users see an error that the file isn’t allowed for security reasons.</li>
</ul>
For WordPress Multisite networks, you can enable this plugin in network mode to control MIME types for the entire network.
<h3>Features</h3>
<ul>
<li>You can control many MIME types and extensions for upload via a modern interface.</li>
<li>Pro Mime Types comes preconfigured by enabling many safe MIME types.</li>
<li>View all allowed MIME types for the site (also those enabled by other plugins).</li>
<li>Every MIME type comes with a security summary explaining why you should or shouldn’t allow it. To view the summary, hover the mouse cursor over the big colored icon.</li>
<li>Accessibility is at the forefront. For example, you can use full keyboard navigation, even for tooltips.</li>
<li>Adds text, code, and miscellaneous file types to the Media Library for sorting.</li>
<li>The Media Library gains support for more file types for sorting images, audio, video, documents, spreadsheets, and archives.</li>
</ul>
<h3>Multisite support</h3>
This plugin can run in network mode, where all sites are allowed one set of MIME types. You can configure the allowed MIME types via the network administration UI.
Alternatively, Pro Mime Types can run in single-site mode, where every subsite has custom-allowed MIME types. Only the network administrator can assign these on a per-site basis.

Pro Mime Types – Manage file media types

Pro Mime Types adds a nifty admin interface for allowing or blocking many file extensions for uploading media, documents, and other attachments.

Correct Audio/Video Uploads vs Pro Mime Types – Manage file media types