Set up a poster board on a wall or easel. Consult your video's script to find the beginning of the story.
Write down the basic premise of the first shot of the beginning on the video on the poster board. Include relevant information like backdrop, setting and characters, and highlight the tension that needs to be showcased to draw the viewers' attention in the beginning of the shoot.
Write or sketch out important shots and action in the remainder of the first act on the storyboard, again showing what characters are involved and highlighting the main script along with any subtext or dialogue.
Draw and write out the shots and action in the second act, along with settings, props and camera angles necessary for the video, on the storyboard. Use another poster board, if necessary. Highlight the needed characters.
Write and sketch out the third and final act, highlighting the finale, on another poster board. Note the characters, settings, props and if any extra cameras are needed.
Assemble the storyboards in order of the shoot and reference them when needed, much like a map of the production.