Foxa, your solution lights up the whole map, which does indeed make it easier to see player models in dark areas.
I was thinking of the opposite though: keeping the map with its current lighting and illuminating the player models themselves like in the video I posted.
I tested out your code though and it looks nice, and I will be using it as a fallback if I don't find a method to light up the player models.
With that being said, I have a suspicion what I originally asked for is impossible without hacks. But just in case, does anyone know if there is really any way to make the player models themselves brighter?