A small LED light on top the camera is very usefull for doing interviews. You don't really need a powerful one, just enough to add some detail and fill in the shadows. A light with a dimmer, or adding a diffuser gel helps to reduce the light output. The problem with a light that's too bright when used in a dark setting like a bar is the camera has to iris down in order to properly expose on the face resulting in a very dark (or almost black) background making it look like a face "floating in space". Another method I like to use with a camera mounted LED light is to use a small ball-joint adapter so I can pivot the light in various directions allowing me to bounce the light off a ceiling or 'throw' more spill light onto the background. You can also use an assistant, hand holding a second light that can be used to fill in the background or add backlight.
