Regarding the text on this page:
http://secrethistoryofstarwars.com/savingstarwars.html

Laserdisc is spelled with a 'c', not a 'k'. (I've also seen it spelled with the 'd' capitalized, for example in Pioneer's LaserDisc logo.)

A disc, or disk, is a flat, thin, round object. Generally speaking, the US spelling is disk and the British spelling is disc, although there is much overlap and variation between the two. In particular the spelling for senses relating to magnetic storage is nearly always disk, as in floppy disk (diskette), hard disk drive, but the other form is used for optical media thus: compact disc, Blu-ray Disc, etc.