In the video, the hen sounds like she has stridor which is when they may have food stuck in the airway. Sometimes you hear this sound from mucous or swelling in the airway too.
Hopefully it will resolve on it's own over the course of several hours. Keep us posted.
Can you get a video or photos of her? For video, upload to youtube and provide a link.
Something stuck in her crop? Have you investigated that - what does her crop feel like? Is it emptying completely overnight?
Are her nostrils clear - they aren't clogged up are they?