Whether you are a student or a facilitator, creating a video to showcase your knowledge/topic beyond the traditional lecture, oral report, or PowerPoint presentation can spike the level of engagement you recieve...as long as you do things the right way.
When it comes to making videos, especailly those meant for a clasroom setting, there are several key points that, as a content creator, you must keep in mind as you begin to the process of making media.
You wouldn't get in front of your class and wing it through your lessons, would you; hoping you cover key topics without a plan? Whether it be a script or a storyboard, you have to know what you are going to say and have an approximation of how you want to say it and convey it visually. Staying on topic, making sure images and sounds match up, and creating an arc that will keep your audience engaged and guides them along the path you are creating are much easier when you are able to justify to yourself in a concrete way the creative choices you make.
While seasoned creators might be able to sit down in front of a computer and freestyle thier way through media creation of a short piece, the average new content creator will need to take thier time and be as exact as possible.
You would not teach an average group of kindergardners the fundamentals of calculus any more than you would try to extoll the need for basic arithmatic to Steven Hawking. In either entertainment or education, knowing what your audience needs and wants from your media is key to it being successful. Aim too high with your content and the point will go right over thier heads; aim too low and your are likely to put them to sleep.
Videos that are too long run the risk of losing thier audience, especailly if you are an inexperienced content creator who is still figuring out how to convey your points effectively.
If you're not making a documentary, movie, or television show, there really is no need for your video to be longer than 15 minutes. When mapping out your content, remember to hue as closely to the main topic as possible. There is no need to put in a review of last week's homework or an overview of topics that will not be covered weeks.
There is also no need to go into details to deeply either; basic information is more than enough. The reason for this is that your video is meant to be an overview of important information on the chosen topic and/or supplimental information. It is not meant to surplant in-class discussion or student research and textbooks.
Videos, by definition, are a visual medium and your video acknoweldge this fact by having more than a series of stacking images on screed or you just talking ot the camera from in front of tour whiteboard. Whether it be animation or live action, including sequences of figures doing things related to your topic is crucial to maintaing your audience.
Never assume that your audience understand what you are trying to say or convey. Always place yourself in their shoes whenever you create and edit. This will keep your video from becoming bogged down in ambiguous statements and confusing imagery.