This is the description given to accompany the video:
Nickel particles float peacefully in a liquid medium until a giant snake seems to swim by and snatch several particles up, adding to its own mass. The self-assembled "snakes" act like biological systems, but they are not alive and are driven by a magnetic field. The research may someday offer some insight into the organization of life itself.
Anyway, see for yourself!
A review of this research work done at Argonne can be found at the Wired website.