Add a Download button below the currently viewing video on oth-regensburg.zoom.us

oth-regensburg.zoom.us_add-video-download-button.user.js

// ==UserScript==
// @name        oth-regensburg.zoom.us_add-video-download-button.user
// @description Add a Download button below the currently viewing video on oth-regensburg.zoom.us
// @match       *://oth-regensburg.zoom.us/*
// @run-at      document-idle
// @version     1.0.0
// @grant       none
// @author      Lukas Wolfsteiner <lukas@wolfsteiner.media>
// @updateURL   https://gist.github.com/dotWee/3124cadda4ad112e5ea33b9761e5353b/raw/a2e79ed7fa0909525abd81d125e3861409bb3c75/oth-regensburg.zoom.us_add-video-download-button.user.js
// @downloadURL https://gist.github.com/dotWee/3124cadda4ad112e5ea33b9761e5353b/raw/a2e79ed7fa0909525abd81d125e3861409bb3c75/oth-regensburg.zoom.us_add-video-download-button.user.js
// ==/UserScript==

document.superListener = document.addEventListener;
document.addEventListener = function(type, listener, useCapture){
    if(type != 'contextmenu')
        document.superListener(type, listener, !!useCapture);
};

function insertLink() {
    var video = document.getElementsByTagName('video')[0];
    var videoSource = video.src; //video.getAttribute('src');
    console.log(video);

    var link = document.createElement('a');
    link.setAttribute('href', videoSource)
    link.setAttribute('download', "download");
    link.setAttribute('id', 'download-link');
    link.style.position = 'absolute';
    link.style.paddingTop = '25px';
    link.innerHTML =`<button id='download-button' href="${videoSource}">Download video - right click here and click <b>'Save link as...'</b></button>`;
    var mainSection = document.getElementsByClassName('main')[0];
    mainSection.insertAdjacentHTML('afterBegin', link.outerHTML);
    mainSection.oncontextmenu = null;

    var downloadButton = document.getElementById('download-button');
    downloadButton.style.backgroundColor = '#008CBA';
    downloadButton.style.border = 'none';
    downloadButton.style.color = 'white';
    downloadButton.style.padding = '15px 32px';
    downloadButton.style.textAlign = 'center';
    downloadButton.style.textDecoration = 'none';
    downloadButton.style.fontSize = '16px';
    downloadButton.style.cursor = 'pointer';
    downloadButton.oncontextmenu = null;
    link.style.cursor = 'pointer';
    changeElementPosition();
    window.onresize = changeElementPosition;
}

function changeElementPosition() {
    var height = getVideoHeight();
    var insertedLink = document.getElementById('download-link');
    insertedLink.style.marginTop = height;
    insertedLink.oncontextmenu = null;
}

function getVideoHeight() {
    return document.getElementsByClassName('player-view')[0].style.height;
}

insertLink();