How would you recommend getting the dog to stop/reduce the behavior if you were an instructor? It might be she can be helped to help you by constructive and kind feedback. Of course the ability to do so varies by person. I know Mr Sca has gotten TERRIBLE at flyball. He is fine when dogs run, he is fine running, then after he runs he goes crazy if any other dog runs

It is getting terrible and I would gladly take feedback on how to settle his behavior, who knows the owner might also
I am dealing now with Leo having similar problem and that is what we are doing. Leo has huge motion sensitivity so when dogs do obedience he is good but when it comes to agility runs- forget it, we are flying to the moon.
It seems Mr Sca once he gets revved up goes to the same place

Most important trick is auto check in/ see Susanne Clothier/
You need to be able to have a relationship with your dog when your dog is asking for approval of his behavior. You do not start at flyball session, start somewhere quiet without distractions, every time pup looks at you- you reward... then go somewhere with minimal distraction- dog has a choice, either go for the distraction or turn to you for cookie, then to flyball session but far away, then closer, then rev him up...
in your case all it might take is to remove Sca out of the room, do few focus exercises, settle command and see if returning back but in quieter state of mind will be fine...
I can see lightbulb going on in Leo's brain when we have cars passing by- " shall I go after car or turn to mommy for the treat?" we finally at the point when slower moving cars at regular streets are not a problem anymore... now we need to cover highway speed and trucks

as far as to class with barking dog... hmm, one agility class we are taking is right next to daycare room which is separated by thin board, sometimes noise is so defeaning I can not hear what instructor says, does not bother Che though... am sure Leo whose sensitivity to noise is much higher going to go ballistic for few sessions