Some court officials also do it near the beginning of The Last Emperor.
Manchu robes in the Qing Dynasty had sleeve cuffs that would cover the wearer's hands. For everyday convenience, robes were normally worn with the cuffs folded up to leave the hands exposed. Flipping down the cuffs were a ceremonial action that implies respect or subservience. That sleeve-flip action is usually followed up with another ceremonial greeting where the person lunges the left leg forward, bends the right knee down, and hangs the right hand down.