Greasy Fork is available in English.
Automatically adds the controls attribute to all video elements.
On gif/videos on 9gag, controls for the video player are shown by automatically, without having to right click and 'show controls', which doesn't always work.
It works by calculating pixels scrolled by user, once the threshold has been passed it will rerun the code add the attribute to the HTML elements.
Please report bugs...
Works for me.