I was able to find some more video's of the series, they may be short but they are pretty awesome! They even have Older Katara and Zuko (I believe) in on of the short clips, plus Korra fighting. The effects look awesome! I can't wait to see it!
In total there are four in the link below ^_^ I love the fighting scenes and her personality! Just Click and watch!
http://io9.com/5876238/first-scene-from-avatar-the-legend-of-korra-shows-our-heroine-kicking-butt