The process by which white blood cells in the blood are attracted to and enter damaged tissues has been the subject of intensive research in the past few years because of its obvious importance in medicine. Apparently it is now understood well enough at the molecular level for this animation of the whole process to have been made. The image of the 'boots' of the motor protein walking along the microtubule, dragging the cytoplasmic vesicle behind it, I find both awesome and comical.
(A clearer version, but with music instead of commentary, can be found here.)
PZ Myers has posted some criticism of this video here. He says that it oversimplifies the movements of the molecules and makes them appear more directed and purposeful than they really are (so playing into the hands of creationists). In reality there would be a much larger random component to the movements made by the molecules. In other words, the 'boots' should not be walking, but dancing!