Making and editing video used to be an expensive exercise, but now cameras and editing software are cheap. As a result many loud-mouths like me have got into making videos to help spread their ideas. There's many reasons to do this, it's a medium with lots of possibilities, it suits people like me who talk well on stage, and there's good evidence that people will pay for video - which is good both for one's income and as evidence that people take it seriously. Despite these reasons, so far I've not taken the plunge.
A big reason why I've kept out of video so far has to do with the way in which I like to learn things - video just doesn't appeal to me as a way of learning. When I'm watching someone talk, and this may be in a video or live at a conference, I'm usually frustrated because things are moving too slowly. I can read much faster than I can listen. With reading I can also skip ahead over bits that aren't interesting. Should I inadvertantly miss something important, it's easy to jot backwards and catch up. As a result I'd usually a skip a talk in favor of a paper.
The same isn't quite true for audio - such as podcasts. While the same issue about slowness and lack of skippability applies, I can listen to audio at times I can't read, such as when I'm walking or driving. But in those situations I can't watch a video either. More than once I've been frustrated by people who publish videos of talks, but miss the opportunity to do an audio-only version.
Still my personal dislike of learning through video isn't that much of a reason to not use it myself. There's clear evidence that people do like to watch video to learn. So since my job is passing on ideas, I should be using the medium.
My primary reason to avoid it is because when I'm writing, I'm not usually explaining things I've already figured out, I'm doing the figuring out as I write. It's often pointed out that the etymology of the word "essay" comes the French essayer, meaning "to try", and that writing an essay is about trying out your ideas. The act of writing something down has often helped me understand a topic, indeed I think that's a large part of why I write as much as I do. I enjoy trying to understand things, and writing for others is a vital tool to help me do that. It may just be unfamiliarity with the tools, but I don't feel I can do that with video, and that is the crux of its lack of appeal for me.