Betamax was a type of human video cassette tape recording format used in VCRs. It was distinct from VHS and was invented by the Japanese electronics company Sony.
The Doctor had acquired a complete collection of Laurel and Hardy films on Betamax from a classified ad. (PROSE: Business Unusual)
The Tenth Doctor stored the Wire on a Betamax tape in 1953 and claimed that he was going to record over it. (TV: The Idiot's Lantern)
In 1982, a Betamax video recorder fell through the Rift to May 2008. It was picked up by Torchwood Three and stored in the vaults. In 2009, when Harold had to get a message to Jack Harkness about the Hokrala Corp, he made a Betamax recording. (PROSE: The Undertaker's Gift)