Yeah, I had tried that the same day I had it installed. I tried HDNET and I think Discovery HD, but no go. It looks like the 5C encryption is set for the national channels, as you said. You must have a device that will recognize the 5c encyption and allow you to record this (depending on what the 5c setting are for that show/channel). At this point I believe only a DVHS deck has that.
