Taiji magic?

Unlike magic, taijiquan skills are real. But akin to magic, unless you are adept at the art yourself, you have no way of knowing how they performed the feat. This is no different to being an acrobat.
How many people can backflip? Play a Mozart piece, build a mobile phone or dive to the bottom of the ocean?

There's no magic involved. There's no trick. You're not being fooled. But there is certainly skill.