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.

kimipooh

The plugin additionally allows the mime types and file extensions to WordPress. In other words, your WordPress site can upload various file extensions.

WP Add Mime Types

The plugin additionally allows the mime types and file extensions to WordPress.

Correct Audio/Video Uploads vs WP Add Mime Types