how to check the location of .iso file that your VirtualBox is dependent on

I've installed a VirtualBox inside which a Windows was installed.

Now I need that .iso file to install on another machine.

Steps:

1. Open Virtual Box and click on the system (Win8.1) icon
2. Click "Details" on the right
3. Move curser onto the "Storage" box and click
4. move curser onto the [Optical Drive] then the path will be shown on Mac