No trick. Liquid dye in water lets us see a Taylor column, which is a physical column made of nothing. Dye creeps around it, or occasionally creates it. We'll tell you how it works, and why it affects more than just an experiment in a fluid dynamics laboratory.
In still air, or water, Taylor columns don't exist. Instead of a column, there is just a little disk or puck on the floor. Gas and water flow over it with no problem whatsoever.
Once the ground the puck is on starts spinning, things change. The disk spins with the ground. The small disk forms a tall invisible column. Drop something inside it, and that something stays. Release liquid (or gas) next to the column, and as the liquid moves, it will part around the column, unable to penetrate it. If you wonder about what kind of ground spins that quickly, creating conditions such as these - you're standing on it.
Taylor columns form because, contrary to many people's expectations, spinning a liquid around doesn't necessarily make its motion more chaotic. It can impose order, because in a spinning liquid particles tend to get nudged back toward their original position like they're in a kind of whirlpool. This helps stem the expansion of released gasses or liquids because, in order for dye to move into a space, the existing water has to move out of it. If the water doesn't move up, move down, or move aside, the dye can't move in. As a result, a spinning liquid can form odd, rigid "columns" of material parallel to the axis of rotation.
The first video shows a column of dye forming in a spinning vessel. This second video gives you multiple looks at how a Taylor column forces dye to move around it, even though it doesn't have any solid barrier. You can also see how dye reacts when the container is not being spun.
[Via Weather in a Tank.]