This is super cool, for both the slick visual effects we see and the clever behind the scenes work that allowed it to happen. Photographer Aaron Grimes made this video of Tokyo, IN MOTION, and blurred certain movements of the city and its people by stacking frames of multiple shots he took and then taking those stacked frames to create a video.
The video's effect does such a great job at capturing what it feels like sometimes to be in a city, the loneliness, the things you miss around you as you walk near people but never with people and so on. Or it's totally like seeing ghosts move around. Grimes explains to Adobe why he did this:
With IN MOTION I wanted to make a busy, crowded scene seem manageable and relaxed. While a time-lapse of a subway platform can look cool, it speeds up everything and the people in it look like insects rushing from one place to another. It almost amplifies the stress of the city. Instead, I went the other direction and toned down the stress of a crowded scene. My favourite side effect of this technique is that when people stop moving, they immediately stand out, giving the viewer something to relate to.
After a lot of experimenting, I brought in a video file as individual layers in Photoshop and stacked them together using the "mean" option. The effect was exactly what I wanted: all the motion blurred together. The more frames I stacked, the more it blurred. From there, I realised that if I staggered the effect by overlapping frames (for example: 1-24, 2-25, 3-26, etc.), then stacked those, and played it back, I would get the motion that I've always wanted.
It's really cool to hear him talk about it. Read more at Adobe's Photoshop blog here.