All in one video pack - 404 page error with WP User Frontend

Hi.
I have installed “All in one video pack” on Wordpress to make a user community board which website users can upload video files on the website.
So I have installed “WP user frontend” plugin to let users post a message on the website.
To post a message via “WP user frontend”, I clieked the Icon - Add Kaltura Media, and new page poped up "404-page not found instead showing the page - video can be uploaded.
Here are the links.
404 error page
http://www.seoulcomputersystem.com/media-upload.php?post_id=0&tab=kaltura_upload&TB_iframe=true&width=640&height=899
but if I add “wp-admin”, it will works.
http://www.seoulcomputersystem.com/wp-admin/media-upload.php?post_id=0&tab=kaltura_upload&TB_iframe=true&width=640&height=899
For the testing, I have loged on the web as a admin account (test/test)
I need a help for this issue, anybody knows about it?