Yes this was derived from film cameras, based on a 180 degree mechanical shutter; However, having a variable shutter is not new and only specific to DSLRs.
For film based motion picture cameras shooting at a frame rate of 24fps, one would think that each frame of film would be exposed for 1/24th of a second; However, with a 180 degree shutter, where half the time it is open or closed, additional time is spent having to advance the film through the gate to be exposed to light, so in actuality, each frame of film is exposed to light for 1/48th of a second. I believe the Panasonic DVX100 was the first video camera to offer 24p and while the guts of a video camera/DSLR are vastly different from a film based camera, intrinsically, the concepts carried over or were replicated in a digital form.