Whether it is a multipart professional development around instructional pedagogy or a quick introduction to printing from your iPad, using videos allows staff to learn at their own pace and on their own time.
When every teacher has to perform the same function, you could call a staff meeting and hope everyone hears the same message, or you could make a screen shot video that can be quickly referenced when the information is needed.
Sometimes several people have the same need, but do not all need it at the same time. An instructional video, placed on a website, can be there to teach basic skills whenever those skills are needed.
Not every video has to be long, in fact, a two minute video seems more likely to be watched than one with too much information.