OK, I took a look at that Samsung link. For OTA signals, you can get DD 5.1 via optical when it is available. Good so far, so you can get multichannel audio out of your TV for OTA signals.
"After you have connected the Digital Optical out jack on your TV to a Digital Optical in jack on your Home Theater System, you should hear sound output from the TV’s Optical jack. You do not need to make any additional adjustments. When the TV displays a DTV(air) signal that is carrying the , the TV sends 5.1 channel sound to the Home Theater."
Now the bad part. With any HDMI signal connected to the TV you can not output DD 5.1 audio via optical. Only 2 channel audio is available.
"If the source is a digital component such as a DVD player, and you have connected the source and the TV using HDMI, and then connected the TV to your Home Theater using Digital Optical connections, you will hear only two channel sound from the Home Theater. Your TV can not transmit 5.1 channel audio from an HDMI digital source through the Optical connection
That is the difference between my Sony and your Samsung. I can get DD 5.1 via optical when any HDMI equipment is connected to the TV. DTS audio does not work, so I connect direct from my Blu-ray player to the AVR via optical for that type of decode.
Funny thing is I did not research this issue before I bought my TV earlier this year. I guess that I lucked out on that.
What I did not luck out on was the ROVI TV Guide. ROVI is dropping the service for OTA signals.