Complex sentence: He decided to remain there, and found a job at MGM Studios, (his sister Norma was under contract at MGM) where he began to pursue an interest in the creation of sound in film.
Split into simpler sentences: He decided to remain there, and found a job at Metro-Goldwyn-Mayer, where his sister Norma was under contract. At MGM he began to pursue an interest in the creation of sound in film.