Is it ok to ask a woman to put her phone down while recording at a concert?
Why are you going to ask her to put her phone down?
I cannot stand people who record at concerts. This might be a good reason to permanently remove her phone and never give it back.
It's rude to tell people to not use their phones if they're allowed to. If it bothers you so much, you should move to a different section away from her.
I know she will never change her behavior though!
She isn't doing anything that she isn't allowed to though. She is entitled to be able to record the concert with her phone if she wants. You shouldn't let little things bother you so much.