This year’s Savannah Jazz Festival will present a documentary about a little organ with a mighty sound. “Killer B3: A Documentary About The Hammond Organ,” directed and written by Murv Seymour, will be presented at this year’s Movie Night. It will be preceded by an organ concert and followed by a question-and-answer session with Seymour. “Over an eight-year period, this story travels to over a dozen cities,” he says.