Alternative video link here, but it's in chinese so no idea if it gives any more information about the source: https://news.ycombinator.com/item?id=37010498

The video is watermarked 炼丹师阿翔 (Alchemist Axiang), which is also the username of the Douyin video, so I think that's the closest to the original source we can get. (The tweet claims Bilibili as the source, but it was apparently a live stream and 炼丹师阿翔's Bilibili account currently only has a previous video without full levitation. https://bilibili.com/video/BV1sM4y1H7MX )

OT but why do I need to press "enable this playback" and reload the page to view the clip? What does it do?

HLS is a way to serve a video in chunks over HTTP. It's how livestreams are implemented in most places. Twitter serves videos in HLS chunks, but Nitter doesn't want to proxy it to you because videos take a lot of bandwidth. In order to let you choose whether you want to connect to Twitter servers, it first asks you whether you want to enable playback.

Because they want to avoid sending your IP to Twitter if you aren't going to watch the video, and the way to do that without JS is to only render the video embed if you actually request it.