Wow. Thank you, Bob! That sounds just like any of my disasters when I attempt any major change in my tanks and ponds or a major rehoming of fish. Always losses, sometimes a few fish, sometimes up to 100% losses. My sympathies. You've learned a lot, I am sure.
I appreciate your honesty too. It takes guts and integrity to describe how one failed for the betterment of others.
Yea, I saw this video before and some others of this vet. He is cool. The down side is it's thousands of dollars we are talking.
The only sensible thing we usually can do is Epsom salts and internal cleansing. Force-feeding is not too hard either but not on a fish that can injure you and not by someone not proficient with fish sedatives.
This floating thing doesn't happen for no reason. The root cause in your case was stress-induced inflammation / infestation of a pathogen.
Perhaps the solution would have been to sedate the fish for the move and/or cleanse them thoroughly well before the move by feeding them with their food e.g., the usual combo of anti-parasitic meds - metronidazole, praziquantel, and fenbendazole - or at least that same Epsom salt magnesium sulfate that kills most (all?) internal parasites too residing in the gut (won't affect those in the tissue, cavity, brain, etc.), to increase the chances of success.