For Dance Floor Riot drummer Seth Donnelly, Thursday night began as an evening of celebration before taking a very unfortunate turn."We were out yesterday — my girlfriend's getting her PhD at Wash U and yesterday was her last day having to actually be in class instead of teach class, so we were out celebrating," he explains. "And I had to go — I'm a videographer for Channel 9, and I had to go out to get a night shot of a building for a documentary.…