Rotate the drum clockwise by hand and look at the central pillar made of pieces of mirrors. You will see a movie. Now rotate it again in the anticlockwise direction and watch the movie. You will find it funny and unbelievable this time.
As the drum is rotated fast the images change quickly but persist on the retina of your eyes for a fraction of a second in sequence producing the effect of a movie. As you rotate the drum in the anticlockwise direction the whole sequence gets reversed giving rise to a funny movie.