Or better said, the people using Photoshop would never cease to amaze me.
The thing I like the most is the way he paints in greyscale and then modifies colors using the Hue & Saturation panel. The use of the Liquify tool to adjust the volumes is really smart too—and quite effective, I've to add. Even if he traced the photo at the beginning, his shading skills are impressive.
Note: before playing, turn off your volume and play some other music. Trust me, you don't want to destroy the bliss of watching this time lapse with the video's soundtrack. [Buzzfeed]