function YouTubeLink( valor )
{
  //o comando GET pega o valor do link(que foi colocado no campo text) e manda para a variavel video.
  http.open("GET", "youtube.php?video=" + valor, true);
  http.onreadystatechange = handleHttpResponse;
  http.send(null);
}

function handleHttpResponse()
{
  //pega o id da div videoyoutube
  var result = document.getElementById('videoyoutube');
  campo_select = document.forms[0].result;

  if (http.readyState == 4) {
    result.innerHTML = http.responseText;
  }
}

function getHTTPObject() {
  var xmlhttp;
  if (!xmlhttp && typeof XMLHttpRequest != 'undefined') {
    try {
      xmlhttp = new XMLHttpRequest();
    } catch (e) {
      xmlhttp = false;
    }
  }
  return xmlhttp;
}
var http = getHTTPObject();