This parameter is effective only if gstreamer 0.10 is selected as the multimedia framework, which results in Totem being selected as the media player. With the default setting for IGEL OS 10.05 and higher (gstreamer 1.x in combination with Parole) the parameter is not effective.
The multimedia framework and media player can be changed in the Registry under System > Registry > multimedia > gstreamer > version (registry key: multimedia.gstreamer.version
).