Add greasemonkey download script

matterhorn.user.js

@@ -0,0 +1,40 @@
+// ==UserScript==
+// @name        Enable Matterhorn Engage Downloads
+// @namespace   https://mh-engage.ltcc.tuwien.ac.at
+// @include     https://mh-engage.ltcc.tuwien.ac.at/engage/ui/watch.html?id=*
+// @version     1
+// @grant       none
+// ==/UserScript==
+
+// Matterhorn Engage supports downloading of streams but it's disabled in the front end.
+
+// Opencast.download.showLinks() fills #oc_client_downloads with download links during
+// page load. The function, however, checks if a certain attribute is set and if yes it
+// doesn't show certain links. We disable that check so that it always evaluates to true.
+var showLinks = Opencast.download.showLinks.toString();
+showLinks = showLinks.replace("media[i][\"tags\"][\"tag\"].indexOf('engage')", '-1');
+Opencast.download.showLinks = eval('(' + showLinks + ')');
+
+// Fix the icon of the download button.
+$("<style> \
+  #oc_player-head-right #oc_download-button { \
+    background-position: -180px -125px; \
+  } \
+  #oc_player-head-right #oc_download-button:hover, #oc_player-head-right #oc_download-button:focus { \
+    background-position: -180px -155px; \
+  } \
+</style>").appendTo("head");
+
+// Save the state of the download button so we can restore it once it has been removed.
+var download_button = null;
+$(function () {
+  download_button = $('#oc_download-button');
+});
+
+// #oc_download-button is detached() from an asynchronous AJAX call.
+// So we've to readd it once all AJAX calls have been finished.
+$(document).ajaxStop(function () {
+  if ($('#oc_download-button').parent().html() === null) {
+    $('#oc_player-head-right').append(download_button);
+  }
+});