A movie... That preaches against tv and movies?
Not quite. That is only a tiny portion of the film and its overall message. Here is how Wikipedia describes the plot.
https://en.wikipedia.org/wiki/Time_Changer
Plot
In the year 1890, Bible professor Russell Carlisle (D. David Morin) stops and scolds a boy named Roger for stealing his neighbor's marbles. He makes the boy return the marbles, and demands he apologize for his unjust action, only for Roger to run away. Carlisle has also written a book manuscript promoting themes of bringing forth Christ's teachings apart from His name. The book is on track to receive a unanimous endorsement from the board of Grace Bible Seminary, until colleague Dr. Norris Anderson (Gavin MacLeod) objects, arguing that teaching morality without Jesus as the standard would be detrimental to future generations. The Dean puts the vote on hold until Anderson and Carlisle work out their differences.
Anderson invites Carlisle to his home later that evening to show him something that would prove his point. Carlisle turns him down, and urges the Dean to proceed with the endorsement without Anderson's vote. However, the Dean firms that the vote must be unanimous. Carlisle finally meets with Norris the next night, where Norris shows him a top secret invention: a time machine invented by his late father. Refusing to believe time travel is possible, Carlisle laughs Norris off as crazy before leaving. However, Carlisle relents and returns to Norris the next night after deciding their differences must be resolved.
Anderson prepares to send Carlisle 100 years into the future. Sending him on a Saturday afternoon, he instructs Carlisle that he has until Wednesday night, and must return to the exact location where he was sent. He further instructs Carlisle not to tell anyone where he is from, nor is he to learn of his own fate. However, Anderson does urge him to find a Christian librarian named Michelle Bain, who helped Norris when he himself traveled to the future.
Arriving in the late 20th century, Carlisle, although fascinated by society's advancements, is shocked at its moral decay: half of all marriages end in divorce, teenagers talk openly about underage drinking, children are disrespectful to their parents and treat moral sins, such as theft, as fun and games. Immodest apparel are openly sold in retail stores,
movies and TV shows contain blasphemous language and inappropriate content. Jesus and the Bible are now banned from public education, and many professing Christians in the church do not really follow Jesus. Carlisle finds Bain (
Jennifer O'Neill), and with her assistance, he learns that society decided to remove the Biblical foundations the country was built on in the 1960s, after deciding that morality was good enough on its own. Finally realizing the error of his ways, Russel begs God for forgiveness.
Anyhow, the movie does a good job, in my estimation, of showing not only the decline in morality, but also some of the causes for it. In this sense, I believe that it is not just entertainment, but that it has some true Christian value to it.