patdpoo,
DNS is nothing scary. It's simply a server that resolves human friendly names such as yahoo.com or google.com to the IP address that computers understands: 67.195.160.76 or 66.102.7.104 respectively. So, we can use any DNS server that is set up properly publicly available for domain name resolution.
From the looks of this thread, those using OpenDNS server is having trouble getting the new ATV to properly stream Netflix movies. I had this issue myself.
To fix, you can make the DNS change on the router or from within the ATV. Making the DNS change on the router means that all computers or devices connected to your home router will use the new DNS server. If you make the DNS change on the ATV only, then only the ATV will use the new DNS server.
For simplicity, I would simply make the change on the ATV as that's the only device with issues. Going from memory so forgive me. On your ATV, locate Settings -> General -> Network -> Configure TCP/IP -> Manually.
If you have connected to you network before, you'll see that most of the needed info is already pre-populated for you. Simply accept those numbers by hitting "done" until you get to the DNS screen. Step by step instruction is below in case you need more hand holding:
1. The first screen is the IP (network) address screen. If it looks like a valid address for your network, simply accept that by hitting "done" or fill in the correct address. Most likely a 192.168.x.x address where x are numbers unique to the router brand you have at home.
2. The next screen is the subnet mask. Should also be prefilled for you. Probably something like 255.255.255.0 Simply accept that by hitting "done."
3. Now you'll be shown the screen asking for your router. Again, if your ATV have been connected to the network and pulled an address from DHCP, it should be prefilled. So hit "done" if there is an address of 192.168.100.1 or 192.168.0.1 or something else if you have a router that employs a entirely different network address.
4. Now, on the fourth screen is the input field for DNS. This is the screen we are after. It'll probably be pre-populated with the router's IP address like the previous screen. If you would like to use google, simply enter 8.8.8.8 and hit "done."
That's all there is to it. You made the DNS change from whatever your router was using for DNS to Google's public DNS server or 8.8.8.8. Now, go back to Netflix and see if that resolves your issue. If not, you may have a problem unrelated to the solution that was presented in this thread.
Good luck.