For the video, upload it to a video platform such as youtube or Vimeo, and copy/paste the link here.
Is the hen exhibiting any other symptoms such as sneezing, rattled breathing, infraorbital edema? If you check inside her mouth, with a flashlight do you see any lesions, mucous, or plaque - how does her breath smell? In the morning, gently palpate her crop, and note whether it's full, or not.