I have an application where I try to load an external SWF. So, we have:
Even with scaleContent set to "true" you still need to set an exact height and width to the SWFLoader control for it to even try resizing the internal SWF. All scaleContent does is instead of showing the SWF at regular or stretched sizes, it also up-scales the SWF if needed, and if not just scales it to retain the ratio of the original SWF.