Hi,
You are fundamentally missing the important differences that have been repeatedly pointed out to you about this.
The idiot in that video (which I have removed ) deprived themselves of oxygen using CO2 at high concentrations for only a short period of time before resuming breathing in an oxygen rich environment.
This does not happen when you use CO2 to euthanise rodents in the correct manner - they are exposed to low levels at first untill they become drowsy and fall asleep then the levels are increased to actually kill them.
At no time do they get put back into the normal atmosphere.
You are comparing apples to oranges in both the method and the effect.
dr del