My experience is the same as ArbolesdeArabia, although I understand the message was different in the leadup to 1975. I certainly empathize with the ex-elder in the video. In my congregation in the 90's/early 2000's I can't think of anyone who dropped out of high school. They also changed their tune in the literature:
"You need to be able to think clearly, speak logically, and read and write well—skills that are taught in school. So take your school courses seriously, as did Tracy, a youth in Florida, U.S.A., who graduated from high school with scholastic honors. She expressed her hope: 'I have always had as my goal to be a full-time servant of my God Jehovah, and I hope my education will help me achieve this goal.'"
-wt 12/1/96 p.18
Even as far back as 1980 they were discouraging dropping out of high school. From Watching the World: "'Nearly one out of every two students dropped out of New York City’s public high schools over a four year period ending in 1978,' reports the New York Times. The information was provided by School Chancellor Frank J. Macchiarola, who said of the 45-percent dropout rate that 'there is no question that our responsibilities to these young people have been grievously unfulfilled.' The New York public school system is the largest in the U.S., with 950,000 students." -Awake 1/8/80 p.29-30
"Christians have often found it advisable to take advantage of standard secular training available where they live. In America a high-school education is frequently of practical value." -wt 4/1/79 p.10
I note the irony in including a piece about half of NYC high school students dropping out in the four years ending in 1978, when they might have contributed to that statistic by encouraging pioneering in "the remaining months" during 1974-75, which was part of the survey period!