Good find, Tony! I've been using the "tongue taste" trick for almost 40 years. But with cylindrical battery you need to use an additional, long enough conductor to do that. The bouncing test is much easier and more hygienic.

The bounce... is a lie.

"Who are you, who are so wise in the ways of science?"

(directed at the youtube guy, and noone else)

That would be a lot more believable if they were the same brand of battery.

well thats something i can try at home without blowing myself up.
in the 50's when making bread board electric gizmos was all the rage for Jr High science nerds we did the tongue test. at least until someone said that you kill a bunch of brain cells every time...

Also, the first battery is dropped from about half the height of the battery' length.....the battery measures about 2" long, and it's dropped from about an inch. The second battery is dropped from twice that height, from almost the full length of the battery next to it...just watch the comparison.
Personally prefer the Duracell, btw...just sayin'