Often confused with soundtracks, which contain mostly source material (songs with lyrics), a score is instrumental music composed and performed for a specific movie. For some people, the only thing they will listen to are film scores and quite a few in the know think it is overall the most interesting genre in present-day music. Funded entirely by a Kickstarter campaign, former CBS TV journalist-turned-director Matt Schrader’s first and, to date, only feature, “Score: A Film Music Documentary” (SAFMD) isn’t a complete overview of a vastly underappreciated and overlooked facet of movie production, yet it is as thorough as it can be with its bullet-point approach. ‘Silent,’ Not Really The first hint we get that Schrader knows his subject matter comes near the start, with the crucial role music played in the success of “silent” films. The role of musicians playing Wurlitzer organs (the first de facto synthesizers) in individual …