Smoothing FLV in a Graphic symbol

I noticed that applying xxx.smoothing = true to an xxx FLV embedded inside a Graphic symbol the smoothing effect does not show up when playing the SWF.
If I convert the symbol instance to MovieClip the smoothing effect works ok: why? I know the Graphic symbol type is very limited, but I didn’t know it prevents smoothing from working!

I can’t find anything about it in the net… :ogre: