It's even simpler then. Just add the Radial blur on the layer itself. With a big enough radius, it's quite all right
Here is your project modified.
You'll notice I destroyed the "focus" object, because it wasn't needed. I grow your layout a bit too, and added a sprite with 8 direction movements (move it with the arrows) and a ScrollTo behavior. You'll notice the blur moves with the sprite.
There is a problem if the sprite isn't in the middle of the screen though, but I didn't find a way to solve this, if anyone has an idea.