Banner adverts and accessibility

Suppose a website displays banner adverts provided by a third party, most likely Google given their dominance in these areas. Suppose one of these adverts were to be an animated GIF or similar. Just who is in for the chop if the advert flashes, strobes or otherwise changes in a way that provokes photosensitive epilepsy and similar?

It goes without saying the adverts causing concern are for dubious get-rich-quick schemes and for programs that claim to have detected spyware somewhere my computer doesn't have. Of course I may have mistakenly installed wine annd tried to give myself crapware just for fun...

And whatever plugin I'm using to reject flash unless I whitelist it is no help. I already checked that was working. Incidentally having 2 pages of Ars Technica open at once is enough to use all available CPU time on the lab computers. I guess that's why the other lab is full of shiny newish dells.

What's my point? Well aside from the therapeutic value of writing this, I'm having to eat my own dogfood, or at least I'm using a screen reader with some of my sites, and just about getting by, and then dealing with a 'prototype' on setbb.com that's infuriating to use with a screen reader and has flashing ads that makes things worse for me. And the cherry on top of all of it is said prototype could have been hosted without adverts if I changed one line of a single text file.