From The TV IV
A cachebox is a device used by television and radio to shorten a program without editing out large portions of the show ahead of time. This is done to squeeze in more commercials without compromising the program being aired. The cachebox begins playing the program, while the broadcast itself is on a delay. As the program continues, the cachebox microedits out portions of the program, on individual frames, where there is little action. Those with sensitive ears could notice the cachebox in effect if there's music playing in one of these scenes, as the music would slightly speed up during the editing. As the program proceeds and the editing continues, the cachebox will eventually synch up with the broadcast close to the end of the show, having accomplished its goal of shortening the program.