If you are changing 50-70% with accurately measured dechlorinated water daily & it's a new tank it's unlikely to be water quality yet. I hope you have a liquid test kit so you can closely monitor the toxin levels.
The video looked to me like the reaction to very early fungus in the gills - they try to scratch their gills with back legs - dog like..
I would give her a salt bath in a separate container (sticky in sick axolotl section) for 10 mins and then add 2 cups of black tea to the tank when you return her to the tank - fridging is not required if you can return her to the tank if the water
temperature is stable & under 23degC . Continue doing the 50% water changes daily & add 1 cup of tea a day with each change. (I'll post the black tea info as a pic)
Never add salt to your tank as it is not recommended and salt baths are easy enough to carry out in a separate tub.
I'm very concerned that the tank desperately needs a couple of decent hiding places - keeping the tank open like yours is very stressful & you won't get the best out of your lotl if its freaking out & can't calm down in its quiet place
<3 >o_o< <3