Hydraulic buck saws on the ground beside both loaders.
That's it exactly, the buck saw lays beside the loader and is connected by hoses. It has a frame to measure the logs against (because on doubledeck sawlogs most mills only give a 3" tolerance on length) and a large chainsaw bar(the one in the pictures is 42")
I watched it...I love the show it's great and I hope they keep it going. To the best of my knowledge it's basically three pieces of machinery....the stumper, which cut the trees, the skidder which drags them out to the deck and the loader which loads them on the trailers. I think the stumper is able to cut the trees to shorter logs....someone correct me if I am wrong.
What you're thinking about is a CTL (cut-to-length) harvester, which cuts the trees to log length in the woods. They are common in the northeastern US but rarer than hen's teeth in the southeast. I have worked in and around the timber industry for over twenty years and have only seen one and it was a demo.
The three step process you're describing is typical of a dry land logger here but swamp loggers also have shovel machines which are very similar to the track log loaders he uses on the deck. The shovels have several duties. When the cutter goes through the woods his first pass is made where they want the skidroad, and the first trees cut are layed down to make a road that the wheeled skidders can run on. The shovels help make this road and then when the cutter moves out away from it they move the trees back to the road so that the skidders can reach them cause if the skidder gets off the log road the shovel has to recover it. The clambunk skidder, (which is the big one that carries the logs above the rear axles instead of pulling them behind), can't pick up it's own logs so the shovel has to load it. The shovels are also constantly repairing and patching the skidroad as the logs move from the skidders dragging logs over them. Swamploggers will start pulling the logs from the back of the tract, (farthest from the deck) and as the operation gets closer to the deck the shovels pick up the back of the skidroad so those logs can get used.
Pictures of a bucksaw, also called a groundsaw. The chainsaw bar is housed in the vertical box on one end and is driven and lowered hydraulically from the loader cab.