It must be DLNA application with server functionality. I know couple of such applications for Android, but I don't know one for iPhone. It is like year and a half have passed, probably you have found one and could share you experience?
You can stream non-itunes friendly media from your computer or iPhone/iPad/iPod to your TV with an Apple TV 2 or 3 and Air Video. The Apple 3 is $99 new. You can probably get a used Apple TV 2 for much less.