Is it the same method with a Mac on safari?
The key is using a browser that keeps a running cache, opening that folder, and capturing the file from the cache.
The file will not have a recognizable name or file type - but as the video/audio load you can recognize the cache file because it grows.
Many times the completed file will not remain in the cache more than a few seconds, so having the cache open as the file loads is key.
(.flv) is the extension for Acrobat Flash media files - and is the most common for this kind of embedment. Occasionally you will get a WMV or MPG - but FLV is by far the most common.