Does anyone know how to achieve this type of effects?
First two seconds show the person rolling backwards with that afterimage.
I can’t figure out how they did it and don’t know what the effect is called so I can’t find anything on google/devforum either.
This effect is created using a ParticleEmitter, Recently I was scrolling the toolbox and found a Deepwoken Particle pack, these might be of worth to you. 
I would reccomend, studying these and paying attention what settings simulate this effect.
Another additional open source VFX:
Thanks, I’ve been stumped on this for a while now.