function render( position ) {
  // position the elements
  var minY = -windowHeight, maxY = windowHeight;
  .each($$hotspotElements,function(index,element){
  var hotspot = element;
  var elemPosition = Number( $$hotspot.attr('data-position') );
  var elemSpeed = Number( hotspot.attr('data-speed') );
  var elemY = windowHeight/2 + elemSpeed * (elemPosition-position) * scrollHeight;
  if ( elemY < minY || elemY > maxY ) {
  $$hotspot.css({'visiblity':'none', top: '-1000px','webkitTransform':'none'});
  } else {
  hotspot.css({'visiblity':'visible', top: elemY, position: 'fixed'});
  }
  });
  
  renderVideo( position );
  }