Note the glowing part. This assumes that your UNRAID server is named "Tower", you have a share configured in UNRAID named "user", and there's a directory under that share named "DVDs".
From my experience, it is best to reference the IP address of the UNRAID server if you have a static IP address configured. Otherwise, you'll need to continue to refer to it by it's "Tower" label.
You can test the share's address in Windows Explorer by typing it in using "\" instead of "/". If you can't browse to "\\Tower\user\DVDs" using Windows Explorer, you WON'T be amount to successfully mount the share in the VM.
Assuming that you have an UNRAID share named "DVDs", you'll want to test the share out in Windows Explorer by navigating to "\\Tower\DVDs". If it is successful, enter into the /etc/fstab file "//tower/DVDs"