Conformity
If there is one takeaway from what you're about to see, is that merely one person needs to speak up and say "no", for the crowd gaslighting to stop being effective.
The next time someone tells you it requires a conspiracy to get people to do idiotic things as a group, you can show them this video — proof positive of why a conspiracy is unnecessary to account for the fact that millions of people can, and often do in fact, shamelessly repeat and obey absurdities in obvious contrast with reality.