The day of SB7 Certified Awesome Stuff roles on.
(both by AppuruPai)
Planetary Folklore describes these as "long exposure shots from the New Transit Yurikamome, an automated guideway train that connects Odaiba to the mainland." But long-exposure can't be all there is to it, right? How would the buildings in the first or the car in the second be (relatively) in focus?
My guess about what's going on it that AppuruPai collected a set of images from the moving train and used some algorithm to pull out the pixels which form continuous curves between frames. (It's like an edge detection problem in 3D.) Those show up as all the graceful arcs. then for all other pixels that are less correlated, select a couple of temporally adjacent frames and average them together, and use the result to fill in everything between the curves. I have no idea if that would work, but it's the first thing I'd try if I was going to replicate this.