<div id="pb_all">
  <a href="javascript://" onclick="progressBar();">
  Скачать
  </a>
</div>

<script type="text/javascript">  
function progressBar(set) {
  set = set || {};
  document.getElementById('pb_all').innerHTML = '<div id="ot" style="width:' + (set.outW || 100) + 'px;height:' + (set.outH || 20) + 'px;' + (set.outB || 'border:1px solid #79a0c1') + ';"><div id="pb" style="background:' + (set.inB || '#e6e6fa') + ';width:0px;height:' + (set.outH || 20) + 'px;"></div></div>';
  var bar = document.getElementById('pb');
  x = setInterval(function () {
  if (parseInt(bar.style.width) < (set.outW || 100)) {
  bar.style.width = parseInt(bar.style.width) + (set.step || 1) + 'px';
  } else {
  clearInterval(x);
  location.href = '$FILE_URL$';
  }
  },
  1000 / (set.speed || 2))
}
</script>

progressBar({step:1, speed:30, outW:300, inB: '#000000'});