It's quite simple really.... he probably did like a huge motion blur or something to the left or right doesn't matter you choose, then started selecting little squares of that layer, copy, paste on background, keep doing then delete that now messed up layer. Hoped that helped. (thank me if it did, button to the left <--)
Oh yes and maybe added like tints to the borders of the squares... I don't know... try it out.
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