Senki Zesshou Symphogear G is an upcoming original anime series, and sequel to the original Senki Zesshou Symphogear. The second season will be directed by Ono Katsumi with animation production by the same company responsible for the first season, Satelight (Aquarion, Bodacious Space Pirates). The series will begin airing on Tokyo MX this Summer.
Senki Zesshou Symphogear G will continue the story of Hibiki, Tsubasa and Kurisu as they combat the ongoing threat of the Noise.
There should be more details about the characters on the official website soon.
If the trailer was eaten by YouTube, you can try this search query to find a replacement.
These screenshots all come from the short trailer above: