This difference in the rate of change of the image is one of the factors contributing to the "video look", familiar to viewers as the more immediate, "live" feel seen in many soap operas and sports programmes.
The expense of videotape and the various mutually incompatible television standards around the world made it impractical at the time for programme makers to sell their productions to foreign broadcasters in their original video form.
The programme is then further processed by interlacing adjacent frames, which halves the running time back to the original twenty-five minutes.
The appearance of these film artefacts on the processed programme would break the illusion that the viewer is watching a videotape recording.
The process has also been applied to a number of other programmes, including two previously lost episodes of the BBC sitcom Dad's Army, which were rediscovered in 2001.
The episodes, "Operation Kilt" and "The Battle of Godfrey's Cottage," were VidFIREd in preparation for their broadcast as part of a "Dad's Army evening" on BBC Two.
(In the case of The Time Meddler the damage was confined to part 4 "Checkmate" but the remaining episodes were left untreated also to match on DVD.).
An easter egg included on the DVD release of The Tomb of the Cybermen featured a brief clip from that serial with VidFIRE processing applied.
Beyond this, the technique (although critically applauded)[citation needed] has seen relatively little exposure, perhaps because of a belief within the broadcasting industry that public interest in the kind of archive television that would benefit from VidFIRE is insufficient to justify the cost of processing.