This post will be shorter than the previous one because there’s a lot of overlap. In both cases, you need to think about things like color, how you’re going to represent the poem’s images, how you’re going to incorporate the text of the poem, etc.
For the video, though, you also need to think about sound. Of course, your video isn’t required to have sound–that’s a choice you make–but it’s an option that isn’t available in comics. Also with your video, you need to think about how long shots will take. Just as the comics scripts need information about how many panels will be on a page, your video script will need to indicate timing and framing for each shot you propose. Be specific about what your vision is.
You’ll also need to consider what kinds of images your video will use. Will it be animation or live action? A series of still images? How will you transition between scenes?
Here’s a link to a Wikipedia article on cinematic terms that might help you find the right language for your vision.