Directional Blur a way to repeat edge pixels?

Hey everyone so i have been practicing whipping to the right and left down etc for when i want this style of transition. I followed a youtuber who creates an adjustment layer with an offset and directional blur, is there a way to clean up this edges when the transition begins, i could live with it but was wondering how much work would be involved to make a successful transition like this, i have heard people say they use a normal blur and do it that way but i prefer to have the motion of the blur in the direction of the whip.

Cheers, 

Any help would be great