If you are in this position you probably discovered already that you can Google tutorials about how to use the equipment and also find plenty of lists of Important Things to Remember. What is missing is the kind of knowhow you normally learn the unpleasant way through experience.
Here are some of these things for people who need to record a video interview: Three Non-Obvious Practical Tips That Make a Difference:
1. Always warm up the interviewee before you start the interview to make them relaxed and comfortable about talking in front of the camera. You can start by reassuring them you can re-record anything that doesn't work but more importantly ask a few other warm up questions before you start the real ones.
2. Keep your own mouth shut as far as possible. Don't comment during answers and after the end of each answer wait a second before you ask the next. If you need to show interest just nod your head. If you overlap your voice with the interviewee then editing the recording will be much harder.
3. And before you do the first two always start the camcorder recording and just leave it recording until you are done. You can delete the warm-up segment later. Don't keep stopping and starting it because this is distracting for both of you and, worse still, there is a risk that you will forget and just when you think you have captured a perfect interview you discover that the camcorder is still on STANDBY.