odpočitavanie začne bez zavolania funkcie

<?php
$video = "videos.flv";

$flv = fopen($video, "rb");
fseek($flv, -4, SEEK_END);
$arr = unpack('N', fread($flv, 4));
$last_tag_offset = $arr[1];
fseek($flv, -($last_tag_offset + 4), SEEK_END);
fseek($flv, 4, SEEK_CUR);
$t0 = fread($flv, 3);
$t1 = fread($flv, 1);
$arr = unpack('N', $t1 . $t0);
$milliseconds_duration = $arr[1];
?>

<div id="text"></div>
<form method="post" name="frm">
  <input type="hidden" name="id" value="<?=$_GET["id"]?>">
  <input type="hidden" name="video" value="<?=$_GET["video"]?>">
  <iframe name="success" src="grayblank.htm" style="vertical-align: top;" frameborder="0" height="1" scrolling="no" width="1"></iframe>
</form>

<a style="display:block;width:725px;height:600px;" id="player" onclick="plus();"><img src="images/play.jpg" /></a>

<script language='JavaScript'>
 var i= "<?=$milliseconds_duration?>";
 var y= 5000;                       
 var casovac = setInterval('plus()',1000);
 function plus()
 {
  document.getElementById('text').innerHTML = i;
  i = i - y
 if(i<-1000){
 clearInterval(casovac);
 success.location.href="succes.php?id="+document.frm.id.value+"&video="+document.frm.video.value;
 }
 }
</script>

var casovac = setInterval('plus()',1000);