Baird mechanical television based on the Nipkow disk, didn’t record anything. A thin spinning disk about the size of an LP with a spiral pattern of holes provided the proper timing and positioning of a flying raster dot as in later electronic versions. At its height of popularity which was short lived, the BBC for example would instruct listeners to tune into one station for the audio, and another for the ‘video’. A second radio with the speaker replaced with a small NE-2 style neon bulb in conjunction with the spinning Nipkow disk, when tuned to the ‘video’ signal, which sounds like grating noise to the human ear, would provide a very crude live motion picture when viewed through a peep-hole/magnifier lens arrangement. Needless to say, it didn’t really catch on, and the development of the vacuum triode and later the vidicon tube quickly made Baird TV a fossil. There exist hobby groups that still make and hack them.
I also read that the mechanical TV was large and heavy, the size of a refrigerator.
You appear very knowledgeable about the subject, did you study it in a college course or pick it up from general interest?