Film stock was the closest '70s film stock reproduction I've ever seen

This film amazes me. The cinematography, hair, make up, sets EVERYTHING is so authentic it puts every other period piece to shame. Even the sound doesn't have a modern feel to it. It has that '70s mono sound and I love it. Does anyone know if they used digital intermediate to get the '70s grainy handheld journalism look/feel? Even the acting felt like the characters were being filmed by a documentary crew(without acknowledging them). Greengrass had a similar approach to "United 93" and I wonder how he gets his actors to give these kind of realistic mundane(compared to the usual fake "everyone is so clever" Hollywood conversations most movies have. Aaron Sorkin is a great writer but no one is ever that witty in real life. but I digess..) performances. It must be some sort of improve technique but even that must have its limitations to an extent. Whatever Greengrass does, NO ONE has ever done it better. Ever. Now he could get typecast(for lack of a better word) as the go-to director for gritty realistic docudramas and with Tom Hanks and his upcoming film "Captain Phillips" we will see how he does with a well known A-list star as a real life person. Thus far Paul Greengrass has done his best non Bourne work with unknowns in this film and United 93. He's got skill.