Kinescope is a device to record 16mm film from a television screen. ABC-TV used this as a back-up copy for the smaller-market stations who couldn't afford videotape recorders, or broadcast the show at times other than the regular network airtime of 4:00pm ET/3:00pm CT (June 1966)-(April 1967), 3:30pm ET/2:30pm CT (April 1967)-(July 1968), and back to 4:00pm ET/3:00 CT (July 1968)-(April 1971) because they were broadcasting syndicated or local programming at that time. The kinescopes were recorded on 16mm B&W film, and continued to be used until 1970. Most episodes of Dark Shadows exist only in kinescope format because the original videotape masters were lost over the years. The only episode that's visually lost and doesn't exist either on film or videotape is episode #1219. A home audio recording of this episode exists.
The episodes that now exist only in kinescope are:
83, 120, 145, 149, 193, 194, 211, 260, 289, 296, 300, 318, 320, 323, 325, 335, 341, 344, 351, 352, 368/369, 437, 509, 683, 797, 813, 1006, and 1017.