Neal Gabler's "An Empire of Their Own" makes the general point that many of Hollywood's early Jewish producers were foreign-born or first generation, and were motivated by a sort of desperate self-determination in their own quests for pieces of the American pie. But more importantly, he notes that, upon Hollywood's inception, many of the important seats in the American entertainment industry (radio, theater, and to some degree vaudeville) were occupied by Jews: for instance, a hugely important individual in RCA's development of RKO, KAO, NBC, and later the very medium of television, was RCA general manager David Sarnoff, who was by the mid-20's already a major innovator in American entertainment. The film industry by and large was a technological shift that used already-established infrastructure, markets, and, more to your point, personnel.