theres a video on youtube showing how it works. Very smart and unobtrusive. Basically theres a sort of blanking plate attached to the underside of the rail similar to the one near the saw that you slide towards the end of the material. just slide the plate as needed, a lot faster than clamps.
Wish mafell was sold in stores here and had more of a presence. My only worry buying their very expensive tools is if something breaks the shipping costs back and forth would be over the top...