He already seems to be a fan of tai chi, as seen in this animation made by John Leo. Why is Vader going through various tai chi forms and movements? I don’t know, but it seems quite cruel to do it in front of a squad of stormtroopers. I mean, they have to be trying their damnedest not to laugh at the Dark Lord of the Sith in his Lift Knee Thrust Upward pose, because a single giggle will get them a red lightsaber chucked through their skull. I guess Darth really is a master of evil. Thanks to Mike S. for the tip.