I don't wanna brag, but in college I was a Telecom major with an emphasis on Video Production. (I chose this because it did not require any accounting classes). Much of my career has included loads of video scriptwriting. A friend asked me for my advice as she was charged with writing her first video script. Here was my quickly composed email to her:
Here you go...as a writer, you need to write first with image and words together. For each moment that someone is hearing or reading your copy, you need to think of the image they are seeing/sound they are hearing.
You sort of have to have audio and video running in you head at the same time. AND - you have to think what can be realistically produced in the time/budget we have. For example,
if you're talking about the concept of "flight" do we see a bird? plane? feather? sky? if a plane is it moving? do we have a narrator...is the narrator seen, unseen? So many questions. Not unlike a print piece...but each answer impacts the produce-ability of the video.
I would say a tip I would offer is, start writing by closing your eyes and see the video in your mind. Hear the video in your mind. Feel the pace. Then capture that. Also, the same way you would allow white space in a print design, in video you control the pace of the viewers experience. So, think timing.
Sorta lame advice...but that how I do it.
Does this help at all?