Instead of complex procedure of spoofing nintendo video server to use nintendo video on 3DS outside US, i have got something very simple.
Just access your wireless internet router and change its Primary and Secondry DNS (i got DNS settings from unblock-us) and you are ready to go. Just like that.
Now i am using netflix on my 3ds and also download Nintendo videos from nintendo offical server.

Please hit thanks if you think this helped you a little.