Flashing world generator

I've just generated myself a new world in 1.8-pre1 and after I moved around for ahile this weird bug happened (Sorry for my english, it's not my native)
When i turned on Use VBOs it stopped happening. And how do I change my player back to 4 pixel arms?

Video:
https://www.youtube.com/watch?v=F7gdig-7hEU