Why haven't say using macro MM_STATE which is in mm_jsapi.h, and implement MM_Init() function like following, otherwise how can invoke the function in jsfl file.
JS_DefineFunction(TEXT("ExportFlash"), ExportFlash, 0);
The Windows 7 path for storing the dll is incorrect. It should be:
boot drive\Users\[username]\AppData\Local\Adobe\Flash CS5 or CS5.5\[language]\Configuration\External Libraries\
Note: by default, the AppData folder is hidden on Windows.