This is the Mellotron

Here is an early sampler called the Mellotron. Each sound was made by lengths of prerecorded tape on a loop, activated when a key is pressed. You’ll see the innards of the thing later in the video. The Moody Blues used one in “Nights in White Satin,” but they only used string sounds. Here you hear prerecorded bits of trombone solo, percussion loops, and well, anything you can record could be put on one of these babies. I assume that pressing the stops, changes the tape loops. I didn’t find the date on this, but I assume it’s mid-1960s.