Wiktionary
blipvert
n. A subliminal or nearly subliminal advertisement displayed for a very short time.
Wikipedia
Blipvert
A blipvert is a very brief television advertisement, lasting one second. The word is a portmanteau of blip, a brief sound, and advertisement.
The term and concept were used in the 1985 film Max Headroom: 20 Minutes into the Future and the first episode of the 1987 science fiction television show Max Headroom. In the film and TV show, "blipverts" were new high-speed, concentrated, high-intensity television commercials lasting about three seconds. Their purpose was to prevent the channel-switching that may occur during standard-length commercials. They were invented as a MacGuffin to drive the plot.