Working out what to show and say in a video clip, even just the key message(s) isn't always easy. Like any task, break it into components. Marketing 101 tells us to start with a communications objective. For example, 'to improve the attitude of brand switchers by 10% over the next six months'. Small businesses aren't measuring 'attitude', but writing a purpose of some sort does define why you are making a video.
I bragged recently to a past client that I'd bought new camera gear and completed extra training and could make an even better video next time. So he put it to me - what would I do? What does make a great video clip?