TeamLab creates gorgeous interactive art installations, like this beautiful piece poetically titled Drawing on the Water Surface Created by the Dance of Koi and People. It's not a video loop, but a program where the swimming koi interact with each other as well as the people wading among them.
From their site:
The work is rendered in real time by a computer program, it is neither a pre-recorded animation nor on loop. The interaction between the viewer and the installation causes continuous change in the artwork. Previous visual states can never be replicated, and will never reoccur.
• Drawing on the Water Surface Created by the Dance of Koi and People
