Bradders1999 uses a magiccarpet hack, as seen in below pictures:
https://2img.net/r/ihimg/photo/my-images/194/20120424214907.png/
Notice the double glass right below him. Whereas the area around him does not have this.
https://2img.net/r/ihimg/f/808/20120424214906.png/
Same here, different location. Notice the before double glass is gone too, please note this is a few metres before the above pic.
Seems suspiciously much like hacking, right?
Never Mind, I saw it having this effect on other players too afterwards, seems like a glass seethrough bug.