I had this working with my UVerse TV sitting on it's own dedicated interface on my pfSense box with 2.2.6, but it seems to be broken with the 2.3 update.
I suspect it has to do with either upstream forwarding or IGMP snooping. My TV STB's work for about about 6 minutes, then when the Snooping times out, the connection gets dropped. However, if I wait a bit, it does reconnect again, but then works until just after the timeout.
Any way to get the igmpproxy which was distributed with 2.2.6 included with the next update? As I understand it, it was patched and these patches were not included with 2.3. I could be wrong.
I also have a /29 fixed IP block which was also working with the IPTV and traffic was separated onto two dedicated ethernet ports on the pfSense box. The /29 is working, but IGMP is no longer.