Media Playback Speed for WordPress
WordPress already comes with a basic video player that you can take advantage of to share self-hosted videos with your audience. Media Playback Speed for WordPress adds playback buttons to your video elements, so your users can adjust playback speed conveniently.
This plugin comes with two hooks for developers to take advantage of. It works with audio, video, and playlist shortcodes. You can use this plugin to adjust the speed of multiple files independently.