As someone with a low-bandwidth connection and that I often work in cafés I hate it when the only description available is through video when there could easily have been text and screenshots.
Even on high bandwidth connections it's annoying. My read speed is much higher bandwidth than videos for things that can be explained in a paragraph or three.
Videos should probably be used when:
1. Your audience is non-technical.
2. A (moving) picture is worth a thousand words (eg, words can't do it justice, but a quick video can).
3. You're not bandwidth constrained (or firewalled).
4. You're not just video'ing text entry, or if you must, you ensure the user can zoom in or enlarge the video to see it (the embedded video can't be enlarged, I had to open it in Youtube to actually see it).
