Yeah you can. I have
Uverse Router ==> PFSense Box ==> GigE switch ==> Uverse TV box.
The trick is enabling IGMP proxy. The first 10 seconds of a Uverse TV stream is transmitted over UDP. After 10 seconds, it switches to multicast. You need IGMP proxy on the PFSense box (or IGMP proxy capable switch) to relay that multicast traffic to the ports on the other interface.
After that, DMZ your PFSense box, add just a few firewall allow rules, and you're done!
My consumer level router I had at the time wasn't capable of doing the IGMP proxy.
Out of curiosity I looked and my Asus RT-N66U does in fact offer it, so more consumer routers may be directly compatible now too.
What the heck? Do you have any clue what the motivation is behind this?
Multicast saves on bandwidth.
Nothing really, but you should generally avoid it if possible. It just creates the possibility of having unexpected problems later on.
You still had to have your TVs run through to the actual U-Verse modem, though, and can't plug them into a router sitting behind it.