The rattling noise in the last video is rales, and can be normal with a respiratory infection when there is mucus in the airways. Overall I think your pullets are looking good. They should get over this sickness in a few weeks. As I said earlier, it could be infectious bronchitis or a mild strain of mycoplasma (MG.) In your first video in the beginning, that pullet looked very sick in severe respiratory distress. But they seem to be weathering this infection well, and getting stronger.
If you are dealing with IB, the chickens could be infectious for up to a year after they recover. If they have MG, they could be carriers for life. IB does not come back on them, but MG can possibly cause illness if they are stressed, such as during a molt, or in very cold weather.
Your set up looks very nice, and you are doing a good job taking care of them. I would recommend changing the food daily since it is wet. Keep us up to date on their progress.
If you are dealing with IB, the chickens could be infectious for up to a year after they recover. If they have MG, they could be carriers for life. IB does not come back on them, but MG can possibly cause illness if they are stressed, such as during a molt, or in very cold weather.
Your set up looks very nice, and you are doing a good job taking care of them. I would recommend changing the food daily since it is wet. Keep us up to date on their progress.