This is nothing new. I can remember when some stupid idiot bought a bottle of Tylenol and put cyanide in one of the capsules, and put it back on the store shelf. Someone later bought it and died from cyanide poisoning. Since then, there is supposed to be tamper evident packaging on all food and drink, and all supplements and medication. This is why you have that inner seal on your vitamins and aspirin pills.
Seems that the ice cream cartons that were tampered with were not sealed. Someone could have just as easily put poison on the ice cream and put it back. Had the companies that make this stuff learned from the cyanide in the Tylenol incident, they would have put plastic film on the carton, so they would only be able to lick the plastic and not touch the contents under it. That would prevent most of these incidents from being serious.
But, the sheer stupidity of posting videos of yourself doing this on the Internet is going to make you a target for jail. You will be caught, since someone is going to see that video that will have you arrested, and any jury will have access to these videos during the trial, making it almost impossible to be acquitted. At least they didn't do that during the Tylenol with cyanide incidents--though several copycat incidents happened with that that ultimately led to the tamper evident seals on our packages. Now, if only they would do that with all our food and drink (bonus: A good seal helps the product stay fresher in storage longer.)