Why are you creating video tutorials? Do you want to answer reference questions in a more active way? Do you want to provide more training opportunities to your users? Do you want to make promotional videos?
Who will create the videos? For greatest quality control, we recommend using a specific staff, as it's very easy to forget how to do things efficiently and well if you don't create videos on a regular basis. If you use a small staff (for example, I am part of the "Enabling Technologies Team" staff and I am the primary user of Camtasia), you will get content from others. Our informationists use Jing to create short, non-edited videos to answer common reference questions.
Who's your audience? Undergrads, graduate students, researchers, faculty, the general public? This will have an impact on how long your videos are (shorter for undergrads; for people who know they need to learn, you can create longer videos) and perhaps on how the content is presented.
How much money can you spend on equipment? If "none" (except your time) is your answer, don't give up hope, just get creative! There are free screen capture programs & free storage spaces as well. Remember that you don't have to create all the videos you need. We regularly borrow videos that we believe are good from vendors and other libraries (with permission, of course).
Where will you store your videos? If you're planning to make just a few short videos, it won't be hard to store them. But if you plan to make videos on an on-going basis, then storage becomes an issue. You can use YouTube for both an archives (some videos are private because they are old) as well as for current videos. University Library has a YouTube channel (mlibrary channel) that we're keeping for the foreseeable future to give our videos a broad audience. We're also preparing to move to a new, campus-wide video management system, which will allow us to store complete videos plus all related materials in the same space.
The answers to these questions will help you focus on length, voice, script, topics.
Something no one likes to think about:
Who will update your videos? Database interfaces change often, & the video you created last year (or even a few months ago) may not be very useful this year. We've thought about many ways to try to do this (using PowerPoints rather than "live" screencasts, so that a few new screenshots could be dropped in), but there's really no way to predict what will change or when. Some options: have a point person who will be actively on the look out for changes throughout your resources or will respond to other staff who see that a change has occurred. Have a plan & try to make updating your videos a part of your workflow.