Hide media previews (video and images) in the HipChat web client

hipchat-hide-previews.user.js

// ==UserScript==
// @name         HipChat Hide Media Previews
// @namespace    github.com/karlding
// @version      0.1.0
// @description  Hide Media Previews (video and images) in the HipChat web client
// @author       Karl Ding
// @match        https://*.hipchat.com/chat/*
// @license      MIT
// ==/UserScript==

var css = '.video-wrap {visibility: hidden;}\n.hc-chat-row:hover .video-wrap {visibility:visible;}\n.hc-chat-row .image-preview-wrapper {visibility:hidden;}\n.hc-chat-row:hover .image-preview-wrapper {visibility:visible}',
    head = document.head || document.getElementsByTagName('head')[0],
    style = document.createElement('style');

style.type = 'text/css';
if (style.styleSheet){
    style.styleSheet.cssText = css;
} else {
    style.appendChild(document.createTextNode(css));
}

head.appendChild(style);