Usually what happens at Hall H in Comic Con stays at Hall H in Comic Con. Unfortunately (or fortunately, depending on your view point) for Warner Bros, they and director David Ayer decided to officially release the footage they showed at the convention over the weekend after a ropey bootleg version appeared on the net. 

Taking to his twitter last night, Ayer said...

This gave us goosebumps. Mainly thanks to Jared Leto's Joker... By the way, the song is courtesy of The Bee Gees. For realz. 

 Via The Hollywood Reporter