Capacitance Electronic Disc
Capacitance Electronic Discs (CED) were one of the more obscure video formats. Available from 1981 to 1986 from RCA, they were based on an experimental format developed by RCA in 1964 which was one of the few formats to use capacitance to store information instead of the more common laser-read optical storage or analog grooves. Disks were kept in protective holders so they didn't have to be directly handled by the user, since they were very delicate and prone to damage from scratches or smudges. Video capacity was only 30 minutes per side, which contributed to the lack of success for the format.
It appears that capacitive formats were developed by at least one other company - JVC developed a capacitive format known as VHD - and possibly two, as there is some reference to a format known as "Fonica" (see the Total Rewind reference for more).