tutorial to "motion blur" people on background

Question

trying to "blur" people on background like this:

example:

but can't find tutorials for such effect.

Could you please suggest some tutorials for this?

Answer 1

I very much doubt that was done in post. It's probably done live in-camera, & took 10 attempts at getting the main subject to stay still enough. You could perhaps fake it in post, but you'd be better starting with a frame empty of all but your main static subject & actual background, to which you overlay other people to then blur. Part of your problem is the feet. Feet stay still whilst the body moves, when walking. You can see that on both blurs.

Here's a very rough attempt, using your original pic & blurring the stationary guy too.

^{Click for full size}
First select & mask the guy to a new layer.

Then burn in the mask.

Using the Smudge tool, with a low strength & a very large, soft brush, gently pull him to one side,

then switch the background back on.

You'd get far better results with a larger image & far more care & attention than I used here.

I did a more extreme one where I bothered to remove the original head first, so you don't see it start to double from underneath…

This is part of your 'best to start with an empty frame' issue - to do this with the subject already in place you not only have to float it out from the background, you also need to remove it from the background, which takes some judicious use of Content-Aware Fill.
You also don't really want your subject at frame-edge, or the Smudge tool isn't quite sure what to do with the edge of frame, as in this case. The edge doesn't really have anywhere to go, so it stays too static. If you faked in some more background behind him, you could temporarily make the frame edge further away, smudge, then re-crop, but that's a bridge too far for a quick demo.