When I was a kid growing up on the farm, I tossed a chicken in the farm pond a couple of times, thinking it was fun. They would immediately swim out of the pond and walk out, kind of panicked. When Dad found out what I was doing he was extremely displeased with me. I did not do it again after he “explained” that to me.
Chicken’s feathers have some oil on them but aren’t heavily oiled like ducks and geese, so they can get waterlogged. But chickens have pretty light bones so they can fly without being weighted down so they will float. They cannot launch themselves into flight from the water like a duck but as long as they are not in a swimming pool or something like that with steep sides, they can swim to shore and walk out. They are not going to drown but if the water is cold and they can’t get out they might get hypothermia.
When it is hot, chickens will wade into water to cool off. I often see mine standing in the water bowls in hot weather, it’s a good way for them to cool off. I’ve never seen a chicken voluntarily walk into deep water where it could go for a swim.
Chickens can be trained. A few years back there was another video of a chicken calmly swimming in a swimming pool on this forum. I wondered how long it took them to train that chicken not to panic when they put it in.
I don’t know what happened before they started filming the video you linked. Chickens are living animals. I can certainly imagine a chicken learning to enjoy swimming on its own, but from what I’ve seen it’s against their nature. Still, there are amazing videos all across the internet of animals doing things that are generally against their nature. With living animals and their behaviors you can never say never.
Was that explained in the same way my dad explained to me? He didn't use his voice when he explained something.