DIY Cheap Flashlight Cinematography: Light people and make it look professional

Our friend Shanks FX explains his little secret about how to use Cheap Flashlights :

I've always incorporated flashlights in my lighting arsenal. And with LED lights getting more powerful, you now can light people and make it look professional. All you need is a few gadgets and some imagination.
Any flashlights that you guys recommend ??? I'm always on the lookout for new ones!!!

Text and video via Shanks FX and PBS Digital Studios