Moving walkways have a big power efficiency problem over a distance. While you can make a train track longer without decreasing the efficiency of the train, a moving walkway has to move that whole walkway. Can you imagine the friction on a 10 mile long moving walkway? You would need massive motors just to budge it.
If, like in the design seen here, the slide movement and propulsion is decoupled, and motors add impulse to the platforms at constant intervals, doesn't sound like that would be a problem. These wood platforms must have weighed tons by the way.
