Etiquette question: phone brightness and filming during fireworks, how do you avoid being that person?

Last night on Main Street during the fireworks I hit one of those awkward moments where I had no clue what the polite move was.

I tend to keep my phone low-key for shows (dim screen, Do Not Disturb, etc.), but I also like to grab a short clip for memories. The couple in front of us had their screen at full brightness, held their phones up the whole time, and at one point they even turned on a light to take selfies. It was distracting enough that people around us started sighing and shifting, but nobody said anything.

For people who go a lot: what would you do in the moment? Do you say something to the folks directly, and if so what wording actually works without starting drama? Do you flag a Cast Member, or is that overkill when it is not a safety issue? Or is the unspoken rule just grin and bear it and move after the show?

I am not trying to police anyone, I just want to keep the vibe good and not have a bright rectangle in my face during the big finale. Would love to hear what you all think is reasonable etiquette for phones during nighttime spectaculars at Disneyland.