VHS beat Betamax by recording two hours of film and licensing the format to every maker.

In 1975 Sony launched Betamax on a half-inch tape that recorded about 60 minutes, neatly the length of an American TV show. In 1976-77 JVC shipped its VHS machine: bulkier and with lower picture quality, but able to record a full two-hour movie on one cassette.

That extra hour rewrote the buying decision. A movie - the dominant thing people wanted to record - fit on a single VHS tape, so consumers angled toward VHS even though Betamax looked sharper. The second push came from supply: JVC invited other manufacturers to build VHS machines and produce VHS tapes under licence.

With several brands promoting VHS and the rental stores stocking VHS titles, the network effects turned decisive. By 1988 Betamax was effectively finished; JVC kept making VHS players until 2016.

Record two hours, and licence the format to everyone

A two-hour recording time covered a full film, which was the single most valuable job for a home video machine.

One-hour Betamax forced users to split or swap tapes for movies, which felt like a limitation rather than a feature.

Licensing VHS to other makers multiplied the machines, tapes and retail listings pushing the format, so the market did the winning.

Better image quality on Betamax counted for less than the practical capacity and the crowd of manufacturers behind VHS.

In a format war the winner is usually the one that decisively covers the user's core job - a whole movie on one tape - and then makes itself easy for rivals to adopt rather than hard.

VHS became the home-video standard of the 1980s and the tape format behind the rental boom. Betamax lingered as a niche and was discontinued in the early 1990s. The case became the textbook example of how a technically inferior format can win on capacity, licensing and installed base.