Mobius Film Strip
Brian used to show short film clips that lasted one to two minutes – these were ususally mundane activities related to family hygiene, technical procedures and such. Many artists have used the effect. Brian took it one step further – his loop was converted to a mobius strip, which caused the film to flip each time, so there was a right and left handed version – which really gave the effect a little kick. Brian probably also knew this as a chiral effect. Look it up!
The image below from XKCD perfectly illustrates what Brian did: