Lighting is one of the most important aspects of video and photography. The basics of which are nearly the same for both mediums. For professional looking results, basic 3-point lighting is your starting point. Set up your first light and put it in front of the talent (slightly to one side) and high as possible at a 45° angle looking down. This is the KEY or MAIN light.
Set another light making this one more diffuse by reflecting it off a wall, a reflector or by putting a scrim (basically a grille) in front of it. This is the FILL light and helps soften the shadows. See the diagram above and note the light is not aimed directly at the talent.
You can also add a light above and behind the subject to add a slight corona (ie. white line) around your talent that helps to separate them from the background. This is called the BACK light.
Basic Three Point Lighting Tutorial by DiCasaFilm