Set YouTube's top header position (the top header will no longer scroll along with the page)
// ==UserScript==
// @name YouTube Top Header Position Relative
// @namespace drev@greasemonkey
// @description Set YouTube's top header position (the top header will no longer scroll along with the page)
// @include https://www.youtube.com/watch*
// @version 1
// @grant none
// ==/UserScript==
var masterhead = document.getElementById("masthead-positioner");
masterhead.style.position = 'relative';