Help explaining the mechanics behind this lego mindstorm biped?

[superfly501]

Hello,

I came across this video of a lego mindstorm

Biped Lego Mindstorms NXT X 2 5 First testing on steps

I only know of using servo's for positional control like that, but looks he is using continuous motors. How do the continuous motors hold position like that? Is it a belt or  gears? Any name for this type of mechanics? I'm guessing his method is much better at fine control than servos. Also is this type of mechanics closer to what we use in modern robotics?

[jkerns]

The Lego motors provide rotation feedback.

So, they can work like a servo except you need to put the feedback loop in your own code instead of in the servo itself.