I agree largely with what he's saying here. Fundamentals drilled to a high degree of proficiency will make your shooting far better than any add on. That has to come first. Once you've done that, you really have to ask yourself what you need your gun to do. If you've taken the time to settle into the fundamentals, you will now have some actual answers to this rather than guesses.
For me, on a rifle, a good sling (the new Vickers type adjustable 2 point) and flashlight are mandatory. This lets you sling the gun and work with hands or effectively transition to handgun with a two handed grip. The flashlight just lets you identify targets. This too is mandatory before pressing the trigger. Everything else is pretty un-needed. After that, a good optic is next. In fact, those three things are the only things I have on my platform.
But again, this comes AFTER you're competent.
As for pistol craft, I'm a light guy as well. You MUST see targets before you press the trigger. I know, it seems to be a midnight shift thing, but there's plenty of houses that you'll want illumination in as well. Please note, I agree, the light won't let you press the trigger cleaner or line the sites up better. But it will paint your target so you know if you need to do those things in the first place.
Good video find.