I've been working on the "no netflix videos" for a few days now, and finally tried something new and got it working. Prior to this I could browse everything, but trying to play would spin the pinwheel, and then go back to the movie description window. Now everything works great and I can stream movies and TV shows from Netflix.
Here is what I did.
1. I connected my ATV2 directly to the back of my cable modem. This worked.
Going with the idea that maybe there is a connection that is being started from Netflix I decided to try normal port forwarding things on the router.
2. I setup UPNP. That didn't work.
3. I setup a DMZ (basically it port forwards all incoming new connections) to the ATV2. That didn't work either.
My final setup now until Apple/Netflix/Me figure out what's wrong and fix it is the following:
I used an old Ethernet switch, and have the these thigns connected to it:
1. Cable modem
2. Linksys E3000 - WAN Port (my main Internet router for my house with lots of stuff behind it)
3. ATV2 Ethernet port
The big difference in this setup is that the ATV2 has a public Internet address as opposed to a private address. If you have more than one Internet device in your house, you are probably using private addressing. Your ATV probably has an address that starts with 192.168.x.x where x any number between 1 and 254.