I've taken the liberty of naming them.
"Reverse Ab Machine Torso Twist"
So it's this machine
except the guy was sitting on it backwards and had the front handle bars+chest padding rotated 180 degrees.
This guy would grab some pretty heavy dumbbells (~40lbs ?) and start swing them at his sides until he gets enough momentum to do what looks like a bicep curl. It's odd looking especially since his whole body is stiff and it's acting as the pivot point to swing back and forth on.
One legitimate grip exercise is to get a stick, tie a long string to it and then tie a weight at the end of that and then just keep twisting it until the weight is at the top and slowly let it back down. There's his one guy who will twist the weights and spin them in place on the racks. The weight ends of the barbell can freely spin so I doubt he's getting any resistance.
"Weighted Human Cork Screw"
I don't even know how to explain this one. Grab two dumbells, pretend you're going to scratch the left side of your back with the right dumbell but keep going until it's past the head and bring it over the right shoulder, back down to the right side of the hip then to the left and repeat. At the same time do the mirror movement with the other arm.
"Alternating Squeaking Cable Flys"
It's like cable flies... almost. Make sure the handles for the cable pulley are squeaky. Position the cable pulley all the way at the top and stand directly in the middle. Grab two paper towels from the restroom and proceed to use them to grab each handle. Position yourself standing straight up with your arms out so that you're forming a Y. Generally not moving the rest of your body bring the two handles together in front of you, near your hips until they just touch then stop any resistance so you quickly spring back into the Y position. Do the same except have them touch behind your back. Repeat.
Grab the 2.5 plate. Get on a treadmill and go at a walking pace. With your arm bent at a 90 degree angle out to the side wave it back and forth in a range of maybe 30 degrees. Repeat with the other hand.
Pick and exercise but only move within a few inches of the full range. That in itself isn't weird but if you see a guy run though a bunch of them all at once, it's pretty bizarre. Here are the inchers variants of some popular exercises:
Squats: Drop down a few inches just out of a knee lock and go back into knee lock.
Leg Press: Load the diagonal sled led press machine up with all the 45lb plates possible. Push it up and down a few inches. Do not disengage that handle that allows for full range of motion.
Bench Press: Position yourself high on the bench such that the pins are inline with your chest/arms. Push the weight up and down but at no point do you ever really unrack the weights.