Sam Fragoso’s short film “Sebastian,” based on letters sent by and to his immigrant grandfather in the middle part of the last century, is a gem. It somehow manages to be assured and ambitious but also self-effacing and seemingly without ego—combinations of qualities you rarely encounter even in the work of veteran directors. The title character (Art Bonilla), a Mexican agricultural laborer, tells his son about his work and explains why, for the sake of the family, he can’t be there watching him grow up. It will be a familiar story to untold millions of people, yet it’s one that rarely gets told in commercial cinema, and in watching and listening to it, we immediately sense parallels to modern day news stories even though that’s not the film’s apparent purpose. It feels like a letter written by a grandson to future generations, memorializing someone who wasn’t famous or important by the standards of history books, but made a world-changing impact on his own family. Sam, a friend and sometime contributor to this site, is comparatively new at directing, but he already seems to know how best to showcase gifted acting, photography, music and editing, letting the work seem offhanded rather than studied, putting moments across by letting them speak and not talking over them. These are qualities that Sam cultivates on his interview podcast Talk Easy, so perhaps it shouldn’t be a surprise that one of his forays into filmmaking would showcase his knack for coaxing stories into being and making them seem as if they would have existed without his help.