There is a problem there but from the video it looks like very thin but not emaciated horses, with long feet but no elf slippers etc. This means to ACO that the animals are not in immediate danger ie not going to drop dead in a week or two , so they give the owner requirements to improve and x amount of time to do it. They are not allowed to discuss the case with you in detail due to privacy laws - so this may be in process, and they "are aware". They are often not keen to seize large animals - I don't know if they have facilities to house and care for them?, so if the animals are not in imminent danger they will leave them with the owner with care guidelines and supervision. It is also a slippery slope when you ad in requirements past feed and water - is shelter a windbreak or a insulated barn, immaculate shavings or deep litter straw, you get my drift. Hopefully this is the case - I have not had any dealings with ACO in this province, just in Ontario.
I am not big on rallys etc, find they can make you look like a hysterical PIA to the PTB, I prefer to try an offer solutions not accusations. Has anyone spoke to the ACO about fostering (I don't think there is a legitimate rescue here)? Organising to have donations of feed and care on standby if they can seize? Can anyone approach the woman in a positive way to see if they can convince her to give up some horses - you catch more flies with honey then with vinegar especially is she is a few fries short of a happy meal. I don't do facebook so if this is all in the works already?
Good luck, if the animals are seized or surrendered I will be happy to donate some time to clean up their feet.
ETA; I guess I am a slow poster - see you are on the fostering/donation path