A common criticism often heard in reviewing documentaries is “it’s more of Dateline segment than a movie;” even good investigative journalism does not in itself make a movie. Sometimes “advocacy documentaries” can be forgiven their school-bookishness because the subject is so urgently relevant; their social or political importance overrides their artistic mediocrity. But how do you justify “The Spy Behind Home Plate,” written and directed by Aviva Kempner? This documentary, in theaters now, is more of an answer to a Jeopardy question than it is a movie. Or maybe it’s an entire Jeopardy episode – as chock full of rapid-fire bits of quirky trivia as it is.