Are you one of those people like me who had this weird problem with Online Videos. When you play videos from online services like Youtube, Google Vidoes. This can happen with any website that hosts flash videos. Flash Videos have their own sound settings.
However, to resolve this problem install the latest version of Flash Player from the Yast repositories.
Switch user to “root” and install latest stable Flash Player:
SAIBABA:~ # yast2 –install flash-player
Once done, reboot your system. This should resolve the problem. Open your browser and play Online videos and you should now watch videos ……..with Sound!!!