https://files.fm/u/u7x6q9t7 THIS IS A VIRUS FOR WORDPRESS. DO NOT INSTALL IT ON YOUR WEBSITE.
A chinese person (in our contact case was AMELIA SMITH (firstname.lastname@example.org) is sending emails from outlook dot com saying they'd pay $50 to $100 per month if you install that. It has a backdoor that lets people upload and delete files from your server.
It is not the plugin https://github.com/sketchmouse/wp-gif-player that @dbedenknecht created, since that one (original) doesn't have the sneaky file in question, wp-inc.php
This "Amelia" is claiming to "verify" the plugin is installed in other sites by mentioning a different file, part of the original plugin.
Again, always check with a programmer before manually installing plugins into WordPress that aren't from wp.com