DESIGNERS APARTMENT / Takeshi Tsunehashi

Here are two wonderful videos from Tokyo-based DESIGNERS APARTMENT (Takeshi Tsunehashi / 常橋岳志)

The first (above) is called "forest". Tsunehashi used Trapcode Particular for the particles and Trapcode Form for the fog. There is also a Japanese version.

"aiiro" uses Trapcode Particular for the particles. 

Takeshi Tsunehashi's website: d-apartment.net