Looking at the video, lots of things come to mind, and it's going to be hard to pinpoint what exactly the problem might be speaking over the internet. If you have a vet familiar with birds in your area it may be worth taking her there.
Dyspnea in ducks can indicate a wide variety of problems. Tracheal obstruction either due to foreign matter, fungal spores, or trauma can sometimes be seen in birds. Frequently, ducks may inhale seeds or debris which can get lodged in their trachea or syrinx, resulting in breathing problems. If a bird is immunocompromised, fungal spores such as aspergillus can cultivate inside the trachea, and cause dyspnea.
Conditions that create increased internal pressure in the body such egg yolk peritonitis, egg binding, or salpingitis can create a strain against the lungs and cause increased breathing.
My first suggestion would be to grab the duck, and with a strong flashlight look into her mouth for anything out of ordinary, or alarming. If there is something lodged further down in the trachea, that will require intervention done by a vet such as a tracheoscopy. Feel her abdominal area, and note whether it's hard, swollen, distended, or soft.
If you're not able to take her to a vet, you may think about getting a nebulizer, and product called oxine. You can make a simple nebulization chamber to set her in using a plastic tote, and deliver the medication in a mist, in which she will breathe into her lungs. That may resolve any bacterial, or fungal problems going on. Unfortunately, for a tracheal obstruction such as seed, there's little to none you can do at home.
