If the floating is causing the axolotl significant stress - and in the video, yours does seem to be working pretty hard trying to reach the bottom - you could try lowering the water level in the tank to a couple of inches deeper than the lotl is long. Alternatively, move the lotl to a covered container of cool, fresh water (100% changed daily) in a quiet, dark place. The water should be deep enough to keep the axie covered but shallow enough so that it is easy for them to stay on their feet. Feed normally, removing any uneaten food after half an hour. Make sure the temperature stays stable - with a small water volume, rapid fluctuations in temperature are possible. Either of these should be considered before anything as stressful as fridging. All the best.