Radial blur but more advanced

Development Character & Animation
1

So I want to create effect that is shown in this video:https://youtube.com/watch?v=4ccBjlAFt0s
But:

  1. I need to know how to eliminate these strange edges of the screen
  2. I have 2 cameras in 3rd person template and I need only one to have this effect
  3. I need to do it so when I press a key (for example “R”) on a keyboard it switches from one camera to an other.
    I need it to be done via blueprints

P. s I am absolute noob, I work with blender but unreal 4 is totally new to me so I probably won’t understand some advanced stuff.
P.s.s I have deadline in 2 days, I would appreciate an answer asap

Thanx!