Explanation of the motility assay of fluorescent actin filaments

Myosin motors can be attached to the surface of the glass slide. These fluorescent actin filaments will bind to the motor domain of the attached myosins. When ATP is added, myosin motors move the actin filaments. These rabid movements can be observed under fluorescent microscope. As the actin filaments appear to crawl across the slide.
This video explains the principle of the motility of actin filaments.