Please don't create low-effort posts like this that criticize / question the veracity of another post with zero evidence or context, it just creates noise and makes it harder for people to trust content posted on Hacker News.
If the above video was faked, and you could post a link or some context showing how it was faked, that would be a good contribution.
Here is an article where they discuss how some of the reactions in the initial version of the video were faked (by an acquaintance of the video's creator who was hired to help), but the creator acknowledged the issue (which he wasn't aware of when he initially published the video) and rectified it by removing those clips from the video: https://www.cnbc.com/2018/12/21/glitter-bomb-video-was-parti...