What makes a good IT Pro video? Here are some starting thoughts - please add yours.

DO

1. Only use video when video adds value. For example, seeing how long something takes in real-time adds value. Likewise, hearing an expert's thought process while troubleshooting adds value. Merely showing the screens you click through for a procedure we can read elsewhere does not add much value.
2. Have some lighting. It should be good enough to distinguish what’s important (for example, a person’s face if they are talking), but spend no more time than is necessary on lighting.
3. Help the viewer understand whether or not the content is for them, right at the beginning. Start with an intro, some text around the video, or both, that helps the user decide if the video is for them. If your video requires expert-level knowledge, say so up front. If your video is about only ONE version of a product or technology, say so up front. If it is only 3 minutes long, tell them. If it will take an hour - let them know. Don't expect viewers to write you a "blank check" on their time.
4. Rehearse sufficiently and prepare your screens sufficiently so that the user is not distracted by typos or confused by work arounds. For example, see the comments on this video.
5. Keep it as short as is necessary, ~ 5 minutes seems to be a sweet spot, and should allow you to dodge the random insertion of commercials into your video by MSN. For example, if you have a 15 minute recording that covers three major issues or scenarios, consider publishing them as three single-issue 5 minute videos that link to each other. Search engines and IT Pro viewers will thank you.
6. Talk like a real person. In written text, we place a premium on clarity and brevity. This is not only for ease of reading, but because it lowers text localization costs. However, if you read it out loud, it doesn’t sound “natural” – like people talking. Just talk on the video in a natural way. Humans respond to other humans speaking in a way that is quite different than reading. Trying to “pretty up” your speech usually does not work anyway unless you have public speaking or acting training. If you have these skills,  training and experience, by all means use them.
7. Provide a transcript, and text titles, when possible.

DON’T

1. Over-produce. You don’t need Hollywood-level lighting or sound or script development. Spend your time on content quality rather than “extra” levels of “production value.”
2. Neglect to establish context. Anticipate the FAQs for your video, and answer them up frontin the video. For example, who are you? What is the video about? What do you expect the viewer to get out of watching it? How long is it? What pre-reqs are required to make use of what you are demonstrating/discussing?
3. Stray from the point.

SteveOLAP leaves a great comment on this video that sums it up: