This trick is one of the iconic rope trick used by many magicians.
Effect - A knot on a red colour rope jumps onto an yellow colour rope. Further this red knot slides off the yellow colour rope and is shown seperately. The knot is now thrown onto the yellow rope and gets attached to it. For the climax, the red knot vanishes and a piece of red rope is seen blended onto the yellow rope. This can be passed out for examination.