I haven't been on a commercial flight in ages, but I recall learning from a friend in the know that the in-flight movies back in the 70s were usually on Super 8 film, and usually back-projected. Some Super 8 collector publications used to have these used Super 8 feature film copies for sale in classified ads, but I never bought any, except for a somewhat lengthy promo reel for the first Star Trek movie in 1979.

Maybe someone else knows more about those old in-flight movies, as far as the film format, etc.

This commercial describes the entertainment available while flying "economy excursion", including feature films, cartoons/newsreels, and even pong games.

The commercial gets the message across well, and from an advertising standpoint is a success.