This does not simply make your videos play at 0.01 x speed. You can smoothly slow down and speed up your footage, optionally with motion blur.
How does slow motion work? slowmoVideo tries to find out where pixels move in the video (this information is called Optical Flow), and then uses this information to calculate the additional frames.
Videos in any format supported by ffmpeg can be loaded. Image sequences can also be loaded, so, if you did a timelapse with too few frames, slowmoVideo may help as well. slowmoVideo does not work with a constant slowdown factor but with curves that allow arbitrary time accelereation/deceleration/reversal. Motion blur can be added, as much as you want.