A couple days ago I changed the Texture Sampler to swap its texture with what's being sampled, so most of the behavior you're seeing in that video is intended... you can certainly butcher a level's texturing with it but I wanted to try it out and see how fun it felt.
The bug there is that you were somehow able to sample the temp "no tex" texture multiple times and stamp it everywhere; my idea with the swapping mechanic was that you could never destroy or duplicate any given texture in the level more times than it originally appeared.