Michael demonstrates two different excersizes here. Note the hand placement. One set is underhand, the other over hand.
This is position is underhand, using the padded cross bar. You can add or subtract connector links determining the height of the bar, depending on your arms length. The padded cross bar adds much needed lateral support to your overall body if you are twisting or working your inner core for balance and stability. This particular excercise is great for buttocks, abdomins, thighs, and calves.
For this excersise, try keeping your legs straight adn moving them easily and smoothly slowing down before coming to the end of each end point. Hold it, breathe, release and go back to repeat.
Remember to breathe. 
Michael uses his hands over the bar this time. Using different hand positions utilizes different leverage for your body while moving, twisting, and shifting your weight. Try also putting your hands together side by side for another style of excercise.
Slowly pull your knees up to your chest. This works the thighs, calves, abs, and lowerback.
Again, remember to breathe and go through the motions slowly, to get the fluidity of the action correct. Practice the excercises correctly at first to get the motion trained in your head before attempting higher repetitions.