If in doubt, take it outside your property and do a reset. It should have a 0 value when the reset is complete which indicates everything is working properly. During the reset, it briefly shows the 221 max before showing 888 and then stabilizes on the true value. If you take it back inside and it shows anything greater than 0, then there really is some level of CO which means it truly is not an error and you really have a CO leak and you should immediately open windows and vacate the premise.
I think a more appropriate video is what it looks like when there is CO detected. Because my detector acts totally differently them what you just demonstrated.
Your unit has reached it's end of life. The unit will chirp twice every 30 seconds . Changing the batteries will not stop the beeping and the unit must be replaced to stop the beeping. If you have a digital display it will say END and does not alternate the number and END. Trying to test the unit does not trigger the alarm other than displaying every digital number like for example 888 .
Your Unit is running low on battery. The unit will chirp once every minute or 30 seconds until you replace the batteries. If you have a digital display it will alternate the number and LO simultaneously . Another thing is Your Unit indicates a Malfunction. The unit will chirp once every 30 seconds. The Beeping will not stop until you replace the unit or call the manufacturers number to find the issue. If you have a digital display it will say ERR and does not alternate the number and ERR. Also Another Thing is Your unit has reached it's end of life. The unit will chirp twice every 30 seconds . Changing the batteries will not stop the beeping and the unit must be replaced to stop the beeping. If you have a digital display it will say END and does not alternate the number and END. Trying to test the unit does not trigger the alarm other than displaying every digital number like for example 888 . Alternately If the unit is malfunctioned or has a critical low battery level it will make a loud continuous tone. Hope this helps