The world turns into a glitchy mess

I was playing 15w41b, testing out the wings but then, the world gets distorted and flashes all kinds of areas.

What I think is happening is that in this large area, the world copy's a few pieces of land in that area and flashes those copies. This video I recently made will explain it https://www.youtube.com/watch?v=RIunL5OEkhs&feature=youtu.be