php – about：src中的空白

<form action="check.php" method="POST">
    <input type="submit" value="POP2!">
    <input type="hidden" name="video" value='<embed src="http://XXXXX" width="712" height="475" allowfullscreen="true" allowscriptaccess="always">'>
</form>

在我的check.php中：

$output = $_POST['video'];
$output = urldecode($output);
echo $output;

$_POST [‘video’]的值来了.

<embed src="about:blank" width="712" height="475" allowfullscreen="true" allowscriptaccess="always">

任何人都知道为什么链接变为about：blank？
谢谢.

编辑：Google Chrome – Inspect Element错误显示此信息

Refused to execute a JavaScript script. Source code of script found within request.