I"ve made hundreds of videos explaining physics concepts, they are all short, about 1 minute long, fast and direct. I speed up my writing x2 and my drawing x 4. I have to speak quickly to get through the text. They all include animations that I often have to make especially for the video. One 1 minute video can take up to 4 hours to make. I think they are effective as a quick revision aid but are too fast to be used...