This video is depicting the four phases of mitosis. The first phase that occurs is prophase, which is the condensing of chromatin into chromatids which bond to a common centromere, and the nuclear membrane starts to break down. The mitotic spindle begins to form as well. The second phase that occurs is metaphase, where the sister chromatids line up across the midpoint of the cell. The third phase to occur is anaphase, where the sister chromatids splt at the centromere, and pull to opposite poles of the cell. The final phase of mitosis is telophase, where two new nuclear membranes form, and the cell splits.