The plant really has nothing to do with it except that it becomes part of the capacitance-sensing circuit in the controller base. The LEDs change color in a programmed sequence when a large increase in capacitance (your body mass) is added; you'll note it also changes when the hands touch the vase alone.
awesome. i saw a lamp like this not too long ago. the base was a planter box with a sensor board at the bottom. i didn't take any video, but this was the lamp: http://tinyurl.com/8rggygl
Capacitance-sensing circuitry is nothing new. Neither is a color-changing cluster of LEDs.