Hello,
That size is the default size that Adobe Flash player recognize the file as being at when uploaded to the system.
However, this does not matter since the resource will always fill the full screen division that assign to.
So, if you screen division is 500x500, that's how big the resource will be stretched to.
And if the resolution of the swf is 500x500 ( or more ) and if the ratio remains the same .. all is well and will look correct.
If you do want to have control over the size of a resource, embed it under a scene using our Editors.
Regards,
Sean - MediaSignage.com