The cast continues to make the talk show rounds (next 2 videos below). Evangeline Lilly appeared on The Daily Show to discuss the movie with Jon Stewart, teasing him about his complete lack of knowledge of the film while Benedict Cumberbatch popped up on Conan O'Brien. The interview itself was ok but the main but was the first real clip with Smaug. Its very brief as a portion of it was padded with stuff already shown in the trailers.
Over at THR, Weta's Joe Letteri discussed the challenges they faced creating the scenes with Smaug. Part of the problem was the impressive size as Smaug ("twice as big as a 747") with unique antomy that had to be taken in account when creating him in the computer. While you don't see it, they actually create a digital being complete with skeletal structure and muscles to help create a look of realistic movement. Since he has wings and other fantasy elements, that required often hand done animation to achieve the final effects. As to that the gold pile, "We had to simulate all the gold coins, every time he moved. Sometimes it was a little, sometimes it was a lot, but it ended up being over a billion gold coins. During some of the action sequences, threre were hundreds of millions of coins moving at once." Another difficulty was the barrel scene that often had to be completely re-created in the computer from the water, to the actors or replacing them digitally. More details here.