first, to be able to debug, you will need to remove the redirect:
change:
$WA_redirectURL = "video_Detail.php";
to:
$WA_redirectURL = "";
next, make sure the problem is not upload file size, try uploading 4 very small files, if that works, then the problem is the php server.
See the following page for information on settings that will control uploading of large file:
wap_upload.asp?page=php2