Its faster than you can extrude plastic. In the video, it is step rate limited by the 8 bit arduino. Its maxed out at 30khz step pulse rate. I just got a 32bit re-arm for ramps board that I'll be using instead. Up to 100khz step rate so it should go faster but really more for smoother motion capability.
It also helps to use good stepper drivers rather than the drv8825 or a4988 that most use.
Another video moving a 123block. This is much heavier than the e3d hot end that I will be using. Should be no problem moving the actual hot end extruder at high acceleration settings.