Semi trucks have non-synchronized (straight cut geared) transmissions which require double-clutch shifting unless you have the experience to rev-match each gear. Below is a shift pattern for a Eaton Fuller 13 speed.

Its a bad pic but ill explain how it all adds up to 13, this is what the shift knob looks like.

Instead of having 13 different gear slots the truck has essentially 2 shift patterns stacked on top of each other. The low range consists of reverse, low gear, 1, 2, 3 and 4th gears. The second range consists of 5, 6, 7 and 8. To flip between the low/high ranges all you do is toggle that black lever on the front of the shift knob while the transmission is in neutral. Not counting reverse we are at 9 gears right now.

A 13 speed transmission is a special 9 speed because each gear in the high range has its own over drive gear. We'll call them 5.5, 6.5, 7.5 and 8.5th gears for my explanation. To shift into these gears all you need to do is pull the transmission into neutral and then push the red splitter knob forward and then reselect the gear you just came out of. This is called splitting gears and you can shift from any split gear to another one or go back/forth in sequence.

See how complicated this sounds? Like driving a manual car it all becomes second nature. Assuming the stick on the left is the splitter, middle stick is the shift lever, and right stick is hi/lo this driver has to shuffle between all these sticks to get his transmission in/out of gear. My conclusion is that he has deleted his air operated shifter functions in favor of looking like a badass while not being able to focus on the road.