A couple articles to explore...
(inclps4udes a brief section on telecine judder
In the "old days" before digital cinema, motion picture projectors would actually display every frame of film twice using a steady 2:2:2:2:2:2... cadence, to reduce the sensation of flicker on the screen. So the projected frame rate was actually 48 fps, or double the 24 fps at which the film was shot, since each frame was displayed twice.
To match the 60 Hz (ie 60 frames or fields per second) rate of video though, those original 24 fps of recorded film footage have to be stretched out even a bit further. The "odd" frames are displayed twice, and the "even" frames are displayed three times, in a continuous "asymmetric" 2:3:2:3:2:3... cadence. The asymmetrical nature of this cadence gives the motion a slight "jerkiness" or unevenness, which is most noticeable on smooth camera pans. That uneveness is what people refer to as telecine judder
My understanding is that the Cinema Smooth feature switches the frame rate of the F5300 to 96 Hz, which allows each frame of film to be displayed 4 times, in a steady 4:4:4:4:4:4... cadence (instead of the usual 2:3:2:3... pattern), thus removing the judder from the motion. I believe it only works with 24p inputs though.
Some prefer the more steady 4:4:4:4:4:4... cadence, while others (who are more used to judder) may prefer the standard 60 Hz 2:3:2:3:2:3... cadence.