I don't think these training tools are intended to substitute for ice or provide cross-training. Experienced athletes will realize that the slow, methodical training can and will develop correct technique. I didn't see caution in the students on the videos, I saw a focus on correctness, which is something that you can't get if the student can just fling and pray, lol.
Training tools aside, off-ice training is vital for figure skating, especially for jumps. Slowing down the athlete and getting them to focus on careful, correct movement and position is vital. I see too many kids doing off-ice where they race through the exercises with sloppy half-baked efforts. These are the same ones that insist that they can land an axel if only the coach would use the harness.
These exercises, done slowly, build muscle memory and correct technique. That's what I see as a coach.