I've taken a short, cropped clip from an old 8mm home movie. On the left side, the film is slowed down 100x by duplicating each frame 99 extra times. In the middle, avisynth gradually blends two adjacent frames to produce 99 intermediate frames. On the right, avisynth attempts to synthesize 99 intermediate frames via a sophisticated analysis to separate out objects from each other, allowing different parts of each frame to be synthesized in a way depending on how the object is behaving.
Normally one wouldn't stretch anywhere near this much, but it is instructive to see how continuous (or not) the result is.