It's known as a tilt-shift, or miniature effect.
Essentially the focus is only sharp in the middle distance, both near & far are blurred. This mimics a shot of a toy town model shot from much closer.
Traditionally it's done with a lens that can actually tilt, but these days can fairly easily be done in post. To get the shot you need to be high up & a long way back, as you'd normally be looking down at toys, & you really need a long-ish lens to 'compress'* the distances to get the best effect.
I have a Nikon camera that can do this [in-camera post] to jpg, but not to video [or even RAW].
In post you can just blur a vignette, top & bottom - it looks most convincing if the field is actually not level, following the main central element of the shot. It's easy enough to experiment in post, as you don't have to commit until you're happy.
There's a decent workthrough on how to do this in Adobe AE [though it's simple enough to do in other suites] - Making a Tilt-Shift “Miniature Effect” Video: Practically and In Post
I also found this - 50 Beautiful Examples Of Tilt-Shift Photography - which personally (if I'm being generous;) I think is split maybe 50/50 with good ones & ones not so great. Study them to see what type of shot works best.
Just for fun, here's one I did in Photoshop in about 2 minutes [actually took longer to make sure the number plates aren't legible ;) from camera to posting. Just a shot of the traffic from my workroom window - nothing special, & I'm not really high enough up or far enough away to really make it work.
*It doesn't really compress, it just looks like it does. [Perspective 101]