I remember watching a video about timelapse photography. There was a moment when the narrator explained that there is a specific trick to make the videos "smoother":
In the timelapse videos which don't use this trick, if people are moving, they suddenly appear at a precise frame, then disappear,
In the videos which use the trick, we have a feeling that they are smoothly moving, like if there was a motion blur.
What is this technique? What is it called? Is it done when taking photos or during post-processing?