After all this time, we finally get something! SEASON 1 SPOILERS!
On October 1st, 2015 a YouTube channel with the name Sarah Tilgner uploaded a video that appears to be cellphone or camera video of the Attack on Titan Season 2 Preview shown at some sort of event. You can see this video with English subtitles below.
The video takes place directly after the events at the end of the first season. Hanji/Hange and others discovers the Titan’s face inside the crumbling wall. That’s when Pastor Nick comes by and tells them not to let the sun shine on it. Hanji tries to get more information out of the pastor but he refuses to speak.
The Attack on Titan anime originally released in Japan in April of 2013. An English dub was released later in 2014. Since then we’ve received a few OVAs, two live action movies (Review of the first movie here), and an Attack on Titan Junior High anime. There’s no confirmed information as to when the second season will become available, but some are speculating that it will come out sometime in 2016.