Make-youtube-pizdato.user.js

// ==UserScript==
// @name         Make youtube pizdato
// @namespace    http://tampermonkey.net/
// @version      0.1
// @description  try to take over the world!
// @author       You
// @match        https://www.youtube.com/watch*
// @grant        none
// ==/UserScript==
/* jshint -W097 */
'use strict';
var d = document;
var b = d.body;
var state = true;
HTMLCollection.prototype.filter = Array.prototype.filter;
d.onkeypress = function(e) {
  if(e.keyCode === 113) {
    makePizdato(state);
    state = !state;
  }
};

function makePizdato(flag) {
  siblings.call(id('body-container')).concat([
    id('content'),
    id('masthead-positioner'),
    id('masthead-positioner-height-offset'),
    id('player-playlist')
  ]).forEach(flag ? hide : show);
  //id('body-container').style['padding-bottom'] = '0!important';
}

function siblings(_filter) {
  var _this = this;
  return this.parentNode.children.filter(function (child) {
    var valid = child !== _this;
    if (valid && isset(_filter)) {
      valid = child.matches(_filter);
    }
    return valid;
  });
}

function hide(el) {
  el.prevDisplay = el.style.display;
  el.style.display = 'none';
}

function show(el) {
  el.style.display = el.prevDisplay || 'block';
}

function id(i) {
  return d.getElementById(i);
}

function isset(a) {
  return a !== undefined;
}