What is the function of the video? Who is the target audience? Anticipated length? What is the tone/style? Need interviews or a voiceover? What does the video need to accomplish? Core messages? Call to action? Examples of other videos you like?
When people see this video, how will they have found it? Where will they watch it (home, work, online, TV, etc)? What do you want the viewer to do when the video is complete?