Youtube is great for finding clips to teach concepts, especially the humorous ones like Escalator temporarily stairs, which is where I left my comment. I've found some great science videos by Science on the Brain that I've used with my children to support their learning of the Digestive System. They loved it and found it the difference in making connections to what they had to learn in class. Students could do commentary or upload video essays. Very useful tool.
Final note: Health conscious persons, pop and juice drinkers, and Health instructors should check out the one on "How much sugar is in a can of soda?". Wow, a life changer!