I can't see the images, but it sounds like windpuffs to me too. The horse I lease has them. The eight-year-old I used to own had them. Once horses acquire them, they come and go to an extent but never really seem to go away. It means their legs were under strain that caused them, at some point, but it doesn't necessarily mean there's anything wrong right now if that's what they actually are.
Both the horses I mentioned have been very hard workers -- but also completely sound for their whole careers despite the windpuffs.