[Espeefan]

Terry, just about all the bulldozers and excavators use gear head motors to power the tracks. They are compact, have the torque, and are really simple, in most cases, to lock a chain sprocket down onto their output shaft.

I wonder if the videos you have seen are Bruder conversioned models? Those models are all plastic, and they are pretty cheap to convert to RC. I've never seen any aluminum models jumping around like a chicken with it's head cut off! But I have seen some rock'em sock'em Bruder models do that.