Well, as long as it took me to get the rocks up (weeks) it would not have saved the grass. It might have prevented some compaction, but that wasn't that bad in the first place. I actually think I made the minimally damaging choice. In fact, I don't think I re-seeded as soon as the rocks were up because it was in the middle of the summer heat. So I had a mosaic of good grass and dead grass that at least looked better than a big huge patch of dead.
Well yeah, if it took you weeks to move the rocks your lawn most likely would have been toast anyway. But watching the video it looked like you were getting it done a lot faster than that.
Herons and nets,,,,, I'm glad I don't have to bother with either of them. My last pond I had a bit of a problem with raccoons and owls fishing in my pond, the herons never found it though. I think mainly because the pond was small enough to not be too obvious, and in the summer the water surface was 75% covered with vegetation which also helped hide it.
My new pond is about the same size as the old one but also has the advantage of being enclosed in a courtyard with tall 6-8 ft walls. We do have plenty of herons around, I see them flying by all the time following the creek that runs past our house about 200 ft away. They are just far enough away, and the pond is just small and well hidden enough that they can't seem to spot it. So no nets for me.
However, if the herons ever did find my pond I think I would just change the nature of my pond itself rather then put up nets. Rather than stock the pond with expensive fish that I might grow attached to, I'd just stock the pond with cheap live heron food and enjoy the herons.
Gota work with nature sometimes, and watching a heron in your backyard doing it's thing seems more appealing to me then looking at a bunch of fish netting strung all over the place.
But that's just me. Opinions may vary.