I recently installed an IPv6 tunnel (Hurricane Electric) over my vdsl connection and use their provided ::/48 on my LAN. I hadn't really thought about it beforehand, but my ATV3 is now using IPv6 to connect to Netflix and being seen by them as US based.
I assume the ATV3 is preferring IPv6 to IPv4 when it is given the choice. Unfortunately there is no way that I have found to turn off IPv6 or change the preferred order
So now I have access to the US content, but the experience is pretty dodgy. Pinging netflix over the tunnel shows about 25% packet loss (depending on time of day) and I get 'An unexpected error has occurred ...." messages quite frequently while watching shows.
Maybe Netflix will get around to blocking this one day (i.e. have Hurricane Electric associate geolocation with their endpoints) but for now it is a free alternative to other unblocking services.
I wouldn't recommend it as a solution though. Apart from the packet loss issue, there is lots of geek work to get the tunnel installed and then set up the LAN routing, but it was a by-product of some other things I'm working on.