Jack,
The lifter mech is based on levers (it's the same as Maelstrom's flipper mech). The actuator pushes the levers forwards and they in turn push the two lifting plates apart. I will post a diagram once I have drawn one. If you are interested, I may part with Donner, as I have another project underway now. PM me if you are interested.

Luke,
The videos show the robot without the wheels attached. The wheels attach on the outside of the robot and are huge. Donner was designed to be a mini Maelstrom.