OK, I got it now. Now sure why Samsung keeps changing setup like that.
If your TV does not have a sticker on the back (or on the side) displaying its MAC address, there is still one thing you can try.
I assume you're using some sort of router to connect to the Internet. If not, borrow one. Connect one computer and the TV to the router. Go into Router Setup and look for devices connected to the router. Depending on the brand, this could be under Status / Local Network / DHCP Table or Attached Devices, etc... You should see the connected devices, their IPs and MAC addresses.
There is another way to look up MAC addresses via a DLNA server, but you'd still need a router for that.
That's all I can think of right now. Hopefully someone will reply with "Hit the Info button when you're on so-and-so screen" or something simpler...:)