Well watching through that video I'm sorry but she had half of that wrong for starters no offense intended and only have her say so that these are tumours .
First off you must put together a dedicated first aid kit for any possiblility you may have to treat, there was little to be seen on the table :-
https://www.gardenpondforum.com/topic/10984-make-a-complete-first-aid-kit-for-koi-and-goldfish/
One of the top koi authors acctually recomends five seperate kits
There are proceedures to go through when using anesthetic on a fish all include checking just how far the fish is under from light sedation right the way down through to heavy sedation where you can proceed in what you wish to do:-
https://www.gardenpondforum.com/topic/10493-anethatizing-you-koi-goldfish-the-various-stages-of/
Cotton buds have a large supply on hand because it requires more than one bud to clean the wound, you never use both ends they are removed from the operatiing area directly after being used.
We were not made aware of possible fish to human cross infection like TB and others :-
https://www.gardenpondforum.com/topic/10992-zoonosis-its-effects-on-us-humans/
"As such precautions should be used".
There was no baby changing mat a great thing that we koi keepers use to treat our fish on
nor wet towel which you cover all but the wound site that you are working on .
I saw no saline solution used in washing out the the site, which is something we always use.
No toothbrush to gently scrub down to clean tissue after the dead tissue is cut away, on this fish the dead tissue was left on which may cause problems later on in its recovery.
There was nothing to cauterise the wound with and I only saw what looked like iodine on the table yet there appeared to be non on the wound site.
We always use propolis at the end of a minor operation its natures way of keeping things clean.
She admits that the so called tumour will grow back again my question here is why put this poor fish through what she has done, a vet would have removed all infected tissue so what indeed was the point of this operation.
If it was an explority type of operation thats fine but to attempt something on this scale no sorry... besides there is a whole different setup for this including a a fish tank, sponge with an area cut out to gently hold the fish, a pump and a good length of air pipe
The sponge is set at an angle to the tank which holds it in place in place a fish tank in which the large sponge sits above the anesthetic.
This has mesured out and mixed into the water bellow the sponge.
A small pump is placed below the sponge to pump the anesthetic via a pipe to the fishes mouth where the anesthetic is allowed to wash over the fishes gills to keep it asleep for the duration of the operation the water then perculates back through the sponge to be pumped back up again across the gills and so on etc etc till the operation is completed and the fish is placed in recovery. I only know this way of doing thing's in theory and have never used it before.
rgrds
Dave