Sergey Biryukov

Recent minor updates for WordPress introduced a couple of regressions when uploading audio and video files:
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<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.

arthurlacoste

Add more files extensions with a new field in your Medias Settings.
<a href="http://irz.fr/add-more-files-extensions/" rel="nofollow ugc">You can check the dev page</a>
You just need to insert your extensions in <code>Settings > Medias > Uploading Files</code> separate by a space (ex : ‘exe pdf rar’), and the plugin does the rest.
This plugin is in french but the translation in english is in progress.

Add more files extensions

Add more files extensions with a new field in your Medias Settings.

Correct Audio/Video Uploads vs Add more files extensions