Be ready: In addition to being well-groomed, plan in advance for sound bites--short, pithy statements that show passion or "net it out" for the viewer--that will be great on camera. As in a podcast, be sure to speak at a normal conversational pace. This is not a race. Slow down so you are articulate and clear.
Relax your face before the video begins: You don't have to smile the whole time. Depending on the subject, a too-ready smile can seem fake or even inappropriate. Smiling with your eyes makes you more approachable on camera. It helps you project confidence, candor, energy and a real passion for your subject. Think about the best cocktail party conversation you have had recently and recreate the business version of that for the camera.
Get comfortable before filming begins: If the interview is being filmed on a trade show floor, for example, and you are not sitting, assume a comfortable stance so you are not shifting your weight or swaying while you talk. If possible, use a chair or trade show booth counter to brace yourself while you are chatting (but no white knuckles, please). Don't step too close to the camera. Some of the worst videos look like the person is about to attack the videographer.
Do a test run: Prep for an on-the-fly video interview by doing a mock interview that simulates this type of scenario. For example, a reporter recognizes you in a cab line at a trade show by your name tag or logo on your briefcase and asks you about your company. The way you would speak with this person, convey concise information and leave them asking for a follow-up sit-down interview is the way you want to handle this type of video Q&A.
For more on Social Media Training, see the January 5, 2009 issue of PR News.