Back in the 20th Century, before computers took over the film industry, we used to edit feature films on 35mm film. It wasn't virtual, it was real. You could hold the film in your hands, cut it with a splicer, assemble it on reels and wind it through a mechanical synchronizer on your table. We did have editing machines but a lot of the work was manual. The sound was on 35mm magnetic film and had to be kept in sync with the picture to the sprocket. There were multiple reels of sound and the sound was not alway continuous on a given reel. Since magnetic film was expensive, the gaps in the reels were filled with rejected or worn out release prints.
You would see other feature films passing through your synchronizer as you ran through the reel. Sometimes images would pop out at you and, if you weren't in the crisis mode, you would stop and look at the shot. If it was really interesting you could cut it out and replace it with a piece of uninteresting fill of the same length.
An old friend of mine got his start in the British film industry and he made a collection of sunsets from Westerns. They were spectacular and he just assumed that they had been optically enhanced. Then he moved to San Francisco and learned that they hadn't been enhanced at all.
The sunset from August 17th of this year.
A minute later.
One more minute