That gasping and gaping can be a sign of a respiratory disease as well as gapeworms. Gapeworms are one of the more rare found worms in chickens. If you can take a few fresh poops in to a local vet, they can perform a fecal float to look for any worm larvae and coccidiosis.
In your other post about respiratory diseases, you did say that you had seen symptoms such as bubbles in eyes, sinus infection, sneezing, and congestion. You had added new birds to your flock at times which may have brought in diseases. I am not saying that your chicken doesn’t have gapeworm, but a respiratory disease could look like the way she is in the video. You can treat gapeworm with fenbendazole (SafeGuard Liquid Goat Wormer) 1/4 ml (0.25 ml) per pound of weight for 5 consecutive days. But the fecal float would save you from doing that if gapes are not the problem.
If you should lose a sick bird, you can get a necropsy by your state poultry lab to get a diagnosis. There can be more than one disease present. Infectious bronchitis may appear with MG. Coryza and ILT are other common resp diseases. Viruses do not respond to antibiotics, but bacterial diseases need to be treated with the right antibiotic. Tylan (tylosin,) LA 200 (oxytetracycline,) and denagard are ones that are used to treat symptoms of MG.