Interviews will add a lot of work to the production of a promo or montage, but they will give the information those videos convey a human face. Interviews are a must in documentaries, and will engage the viewer more than voiceover narration. Here is a clip from a behind-the-scenes documentary featuring interviews I did several years ago that illustrates the following guidelines for shooting and editing interviews:
1. Shoot with two cameras. Even if you're interviewing just one person, set up a medium shot as well as a close-up. This will give you some editing choices. You can cut between the two angles to remove a pause or whole segment of the interview. Two cameras will also give you backup audio. If you're interviewing more than one person at a time, lock down one camera with a shot of everyone while the other camera with an operator goes in for close-ups.
2. When editing, look for sound bites. We all know that talking heads are boring. So just find short segments of the speaker hitting the main points. And whenever possible, cut away to examples of what the speaker is talking about. If the interview is about worship, for example, let's see some worshippers. I generally try to keep the shots of the interviewee down to no more than five seconds.
3. If the interviewer is off camera, do not use their voice in the edit. It doesn't look good to have a disembodied voice asking a question. Ask the person being interviewed to rephrase the question in their answer. Another option is to turn the camera around and get a shot of the interviewer asking the questions, even if the interviewee isn't there anymore.
4. Get your interviewee to talk and talk and talk. Encourage your subject to get into detail, assuring them that you will edit everything down to size. When they know they can risk being boring, they will give you more. And it is in these long discourses that perfect sound bites can be nestled.
5. Let the interview be the narrative structure. I have rarely written and recorded narration for a documentary. If you have hours of interviews, you will have everything you need to tell the story. It takes a very long time to sort through the recordings, but when two hours has been cut to ten minutes, you will have created true Video Magic.
It also doesn't hurt to have some fun with interviews. After making three behind-the-scenes documentaries about one children's drama team, we decided to go crazy with the fourth. We thought this would cross the line and we wouldn't be asked to do this anymore. Alas, they showed it to the congregation and came back for more.