As an on-camera light, the Lite-Panel LED is hard to go past. The ability to trim the brightness for any given lighting situation is important and this light allows you to do that. The daylight balanced 50 degree model works best as an on-camera light in my experience.
Use a piece of CTO correction gel for the tungsten lighting situations but you will loose some output as you'd expect. It's perfect for a night shoot inside a car and the wider beam of the two is more versatile.
Rosco LitePads also work nicely and have the ability to fix any lighting holes; those places where you find hard hide a light. Interior scenes in vehicles at night are nicely taken care of with LitePads along with so many other potentially tricky situations. These are my favourite light because of the different shapes and sizes that are available.
The great thing is that when you use it, nothing feels lit. It just appears like you've gotten lucky with soft natural available light every where you point the camera and we all know life's not really like that. It's the balance of light's output on the subject compared to the background that's the key to making it work.
As long as you can get the light reasonably close to your subject, remembering that if it’s a daytime exterior interview it’s a little harder to fill; the ambient daylight level will probably be quite high in the first place. The small on-camera light panel is even good used as a key light in low ambient light situations. It’s in the great sunny outdoors that you find there is not sufficient output.
I’d go for the wider beam version. It performs better as an all round camera light, but you'll have to power it from a separate battery (9v to 19v) in say a waist bag, as the battery provided clips onto the back of the light and makes the camera far too top heavy. It's no Sun-Gun, but a beautifully subtle lighting tool for video.
© 2013 Pieter de Vries ACS