Youblock is a greasemonkey script to block YouTube live streaming spammers by clicking flag for spam.

YouBlock.js

// ==UserScript==
// @name        spammer filter
// @namespace   spam
// @description created to filter people from youtube chat rooms
// @include     https://www.youtube.com/*
// @version     1
// @grant none
// ==/UserScript==
var names = [
];
var listenForAllComments = function (e) {
  if (e.target.querySelector) {
    var allcomments = e.target.querySelector('#all-comments');
    if (allcomments) {
      allcomments.addEventListener('DOMNodeInserted', function (e) {
        var flag = e.target.querySelector('button[data-action="flag"]'),
          author = e.target.querySelector('.author'),
          authortext = author ? author.textContent.trim()  : '',
          target = e.target;
        if (flag && authortext) {
          flag.addEventListener('click', function (f) {
            names.push(authortext);
            target.parentElement.removeChild(target);
          });
        }
        if (authortext && names.some(function (f) {
          return f === authortext;
        })) {
          e.target.parentElement.removeChild(e.target);
        }
      });
      removeEventListener('DOMNodeInserted', listenForAllComments);
    }
  }
};
addEventListener('DOMNodeInserted', listenForAllComments);