You're referring to a viral video. There have been many viral videos over the years. To pinpoint the exact video you're thinking of, I'd need more information. However, one option that comes to mind is the 2019 viral video of a TikTok user named Jalaiah Harmon, who posted a dance video that became extremely popular.
However, another option could be a viral video that was posted by a TikTok user named Zach King. He posted a video that made people think they were seeing a real illusion.
