This biography covers the entirety of Steiner's life, from his rather privileged beginnings in Vienna. Interested in composing and conducting from boyhood, he went to England, and he had some success working on musical productions there, but then WWI broke out and he was afraid of being jailed as an enemy alien, so he boarded a ship to America, landing with 32 dollars in his pocket.
He worked on the musical comedies that were popular in the 1920s, and then sound came to film. For most musicians this was the death of a livelihood - No longer would orchestras be needed to accompany silent films. One orchestra would supply the music for one film to the whole world. Fortunately for Max Steiner, he was to be head of that one orchestra for newcomer RKO studios, a studio created in 1928 just to deal with sound films. At first after sound film began, musicals were very popular, but audiences grew tired of them and so sound films were being made with talk and no scoring. You can still hear them today. The actor stops speaking and all you hear is dead silence and some static from the primitive recording technology. Steiner started scoring some of these early sound non-musical films, and the results were well received. So Steiner essentially paved the way for non musical films to be scored.
In 1937 Steiner went to Warner Brothers and was under contract to them for 16 years where he did some of his best work. In 1939 he was loaned out to David Selznick, his old producer when they were at RKO, to score Gone With the Wind, probably his greatest individual achievement, being the longest musical score to date, though he won no Oscar for it. There is also a discussion of Steiner's work process and how he would go about composing scores for films and matching them to scenes along with the technical assistance that was necessary to do that matching.
Steiner managed to never lose his edge in being able to score films that resonated with contemporary audiences. He was having real money problems by the late 50s considering his over generous ways when the score for "Summer Place" became a big hit in 1959 among teens and on the pop charts and solved his money problems with its royalties.
Steiner really did pave the way for John Williams, who is the closest thing to his equivalent, and all of his great scores starting in the 1960s..
The documentary puts the meat on the bones of my outline here, including a fascinating piece on how so much of the material from Max Steiner's career is now archived at BYU in Provo, which offhand seems like an odd final resting place for Steiner's work.