It's incredible how much of the world of Game of Thrones is built digitally. You kind of assume a lot of it is when you're watching, but to see it broken down like this is amazing.
(If you've heard about the gore of Game of Thrones, there's none to be seen in this video. Nor is there any real spoilers if you've never watched the show or read the books.)
Direct link to the video
They do film a lot of it on location around the world (Ireland, Croatia, Malta) which probably helps the actors as opposed to standing in front of a green screen.
Now when is season 5 going to be available?