A few more times the other two should catch on to scenting on water. I had a super good female that was a water dog. She would work it like that female and at times if the water was to deep she even would swim and carry the line. I would start running my pups with her in area's with water and after a couple outings the pups would also catch on. Not all are created equal, but a pup with a good water dog has a better chance of learning.
Johnny T- I am impressed, being a Michigan hunter seeing that swamper run and the dogs work it was something to see.
Mr. Taylor has a good eye, I saw the same thing, the other two in the pack look like they are almost there to run through the water like the first dog.
We have almost the same thing on the Hard water in Michigan, they walk it across the ice, close but not like what your dogs did. Nice video.