philicorda wrote:

Excuse my ignorance, but what is a layback deck? A little googling shows
it to be something to do with transferring sound to video, but I'm none
the wiser.

A layback deck is used to put the final audio mix onto a videotape, or sometimes to prelay the audio track for something like a music video which is edited to the audio track.



What's the difference between a layback deck and a reqular one, and why is
a specialised machine required?

It's recording on videotape, not audiotape. Weird speeds, weird track widths, weird bias.