Just curious what type of media extension are you trying to do?
The PS3 holds Audio, Video, Music and pictures. Has a full browser complete with flash support on the native XMB. You can watch Hulu, youtube, movie sites right from PS3's browser.
About the only thing I can think of is you can't physically download files music, video's to the PS3 unless you're using their PSN server to get your video's.