PHP headers to stream a wmv video file

Question

When I point directly to the file it plays in the browser, but if I try to play it through PHP it does not work. My code is:

<?php
$file = 'videos/video.wmv';
$file_name = 'video.wmv';
$file_type = 'video/x-ms-wmv';

header('Content-Description: File Transfer');
header('Content-Disposition: filename="'.$file_name.'"');
header('Content-Type: '.$file_type);
header('Content-Transfer-Encoding: binary');
header('Content-Length: ' . filesize($file));
header('Cache-Control: post-check=0, pre-check=0');
header('Pragma: public');
header("Accept-Ranges: bytes");
header('Expires: 0');
readfile($file);
?>

It works fine with PDF, rar and zip files, but not on streaming video. The WMP window appears but the video dont plays.

Thanks for any help.