What was the inflight entertainment in the early seventies? In her 1970 song "This Flight Tonight", Joni Mitchell sings


  I'm drinking sweet champagne
  Got the headphones up high
  Can't numb you out
  Can't drum you out of my mind
  They're playing Goodbye baby, Baby Goodbye
  Ooh ooh love is blind


The Sony Walkman first came out near the end of that decade. So what was Joni listening to on that fateful flight?



I will award a 100 point bonus to anyone who can identify the plane she was on in the song based on the lyrics.
During that time, the in-flight entertainment mostly available on flights was radio1 and/or TVs. Although it was not on all flights. Oops, that is true even today.

The radios may or may not have channels. If they had, there was a knob on the armrest, next to headset jacks, to switch channels. The headsets were pneumatic units like this:



The in-flight movies were shown using one or more common CRT TVs mounted on ceilings or walls and audio could be heard using the headsets. The first time a movie was shown on an international flight was in 1962 by PIA. It was more like the picture below but instead of LCD monitors, there were CRTs.



In mid-seventies, Braniff Airways was the first airline to offer video games in-flight.

By 1979, electronic headsets replaced their pneumatic counterparts, which improved audio quality.



Wikipedia has a detailed article about the history of in-flight entertainment:


  In 1971, TRANSCOM developed the 8mm film cassette. Flight attendants
  could now change movies in-flight and add short subject programming.
  
  In the late 1970s and early 1980s, CRT-based projectors began to
  appear on newer widebody aircraft, such as the Boeing 767.


This website has nice slideshow about the history.



1: Not actually a radio, but recorded audio