Writing the script, creating storyboards, preparing a production schedule, auditioning talent and preparing the cast, hiring and preparing a crew, securing equipment, finding and securing locations, selecting wardrobes and so on.
The production phase is where all the raw materials for your video will be captured. If you have specific visions, ideas, or visuals that you want to be included in the final product, be sure that you have clearly communicated that with your producer before the end of the production phase.