Video is a remarkable medium for communication and has captivated me completely for the past ten years. I have spent a good deal of time thinking about why video is such a powerful tool and can sum it up fairly quickly.
We can't ignore a pretty face (or any face for that matter) The fusiform face area (FFA) is a part of the human visual system that, it is speculated, is specialized for facial recognition, although there is some evidence that it also processes categorical information about other objects, in particular familiar ones. It is located in the fusiform gyrus and makes it almost impossible not to be drawn in by visually processing a human face.
83% of human learning occurs visually. I am naturally a very visual learner, although when I was in school there was not a system in place to teach in that manner. Instead I would memorize by closing my eyes and visualizing the answer and memorizing that visual cue. Apparently a large majority of people also process information similarly.
Movement triggers fight or flight, this is why autoplaying videos on a platform like Facebook are such effective marketing tools. Nothing else on screen moves, the movement focuses enough attention to create enagement.
Audio & Visual medium overruns our emotional systems releasing key hormones. we cry at movies because the oxytocin in the human brain is imperfectly tuned. It does not differentiate between actual human beings and flickering images of human beings.
Beyond all of the above I believe it is the unique potential for storytelling that makes video such a compelling medium. It never ceases to amaze me how advanced we have become at crafting video that connects to people and shares stories, educations and compells so damn well.