Hey Yandi I think I am having the exact same problem

Qt Code: 
  1. Starting /home/agron/QtSDK/Demos/4.7/qmediaplayer-build-desktop-Desktop_Qt_4_7_3_for_GCC__Qt_SDK__Release/qmediaplayer...
  2. Media Player(10178): couldn't create slave: "Unable to create io-slave:
  3. klauncher said: Unknown protocol 'rtsp'."
To copy to clipboard, switch view to plain text mode 

Looks like it's been some time since you reported the error, but did you ever make it work?

Is your distro OpenSUSE 11.4?