Video is the most effective medium for communicating information in the shortest amount of time. Most people are visual learners, and when combined with an audio element, ensure a higher likelihood of knowledge transfer. Studies show that humans only retain 10% of the information they hear vs. over 50% when they see and hear.
Easily Produced
Because of the advances in cameras, smartphones, and video editing software, video is the easiest and cheapest to produce. It no longer takes an expert to deliver high-quality video that people want to consume.