A couple of school buddies share many hobbies, including a love for music and a secret passion for the same girl. One of them teaches himself Michael Jackson's signature moonwalk. However, once they leave school, they have to make do with reality. One makes a living by hosting weddings, while the other becomes a barber.

The teenagers grow into middle-aged mediocrity. But they have never given up on their dream of making it big. They team up to compete in a singing contest, one plays the guitar and the other reprises the moonwalk. They sing of "life as a ruthless knife that changed our looks, of flowers that withered before they had a chance to bloom, and of youthful days that galloped by without saying goodbye, leaving us deadened and bloodless".

This is the plot of Old Boy, a 43-minute film that spread like wildfire on the Internet in early 2010, attracting tens of millions of viewers and inadvertently kick-starting a cultural phenomenon known as "microfilms".

Short films have existed since the late 19th century when the medium was invented. But what distinguishes microfilms from traditional shorts, as they are known by the professionals, is the distribution platform. These films are not meant for theatrical release. Instead, they are made with the desktop or mobile screen in mind.

The sudden popularity of microfilms attests to the wide use of technology, which "enables people to get information on the go and piecemeal", says Yu Xin, a film critic. "The trend is going in the direction of information fragmentation, dumbing down and acceleration." In that sense, a microfilm is like a video tweet, to be posted online and passed virally from gadget to gadget.