If a flash website is using outsourced (non-embedded) audio/video/images is it possible to capture the location of these objects? Either by tearing into the flash file or possibly using a side program that tracks requests by the browser?
Not easily. Even reverse engineering the swf yields little to nothing of the actionscript, so you're safe there.
But, tracing HTTP requests will allow you to do this - but it's not easy.
Basically, I always work on the assumption that if I'm putting anything on the web then it's at risk of being used elsewhere. Check your logs to see if these files are being accessed by anything other than your own site if you are sensitive to them being used without permission.