In this thoughtful video from Dedo Weigert, "catch lights" (or "eye lights") are analyzed in-depth, with many examples and explanations as to what different effects are created by their use. Placement, intensity, shape, and direction can all play a subtle but very important role in when it comes to a catch light, and what a director or cinematographer wants to communicate from their character can drive that decision.
Informative videos on lighting that really dive deep into the meaning and emotions created by light are some of my favorite videos out there. It's so interesting to see firsthand how small changes can dramatically impact the message that is being conveyed. When done well, the lighting look created combined with the talent's expression can speak more than any dialog could ever do.
In most amateur projects I watch, the placement of the catch light seems to be an afterthought, where not much consideration was given to the catch light specifically. Instead it's usually a byproduct of lighting with something like a rembrandt or glamour look, which still gives a nice catch light, but it's just as much about the shadows on the face as it is light in the eye. When going for an emotional close-up though, that's when you're likely to get the most impact out of a crafted eye light.
Have you seen any in-depth videos that really get into the minutia of lighting, and how it subtly affects the emotion of a character or scene? Or maybe how compositional elements can create different feelings in the background of your interviews/headshots? Share them in the comments if you can think of any.