I'm having a similar problem using the youtube API. It seems to be an issue with SWFLoader and youtube videos (not sure if it's just youtube videos that are the problem). It's reproducible if you just do something like:
<mx:SWFLoader source="http://www.youtube.com/v/Gi-icnwfqo8"; id="myVideo" height="300" width="400" scaleContent="true" maintainAspectRatio="true" /> Where the source is statically set. I can fix it by changing scaleContent to false, but that's not really what I want. Any thoughts? Thanks, Ryan
