> A telesync (TS) is a bootleg recording of a film recorded in a movie theater, often (although not always) filmed using a professional camera on a tripod in the projection booth. The audio of a TS is captured with a direct connection to the sound source (often an FM microbroadcast provided for the hearing-impaired, or from a drive-in theater). If a direct connection from the sound source is not possible, sometimes the bootlegger will tape or conceal wireless microphones close to the speakers, as it is better than a mic on the camera. A TS can be considered a higher quality type of cam, that has the potential of better-quality audio and video.
This has an analog (so to speak) in the live music bootlegging subculture. If you can convince the roadie running the mixer or the sound board to plug in your shady recording device, then you can cut a bootleg record or tape which advertises that as a selling point.
Live audio bootlegs of concerts are typically plagued with the same sort of interference, such as crowd noise, shaky everything, cheap microphone designed for voices only, overwhelming decibel levels, etc. A "clean soundboard" recording can bypass all that and sound comparatively good, especially if the band is good at playing live.
https://en.wikipedia.org/wiki/Telesync