Manipulation is the ability to interact with objects: pick them up, orient them, place them, use them, or assemble them. For humanoids, it is often harder than walking.
The hard part is not moving the arm through space. Industrial robots have done that for decades. The hard part is dealing with ordinary objects that shift, deform, slip, reflect light, block the camera, or appear in a slightly different place than expected.
A useful manipulation demo answers three questions: did the robot perceive the object correctly, did it choose a grasp or action on its own, and did it recover when something went wrong? A video that shows a perfect take with no context may be impressive, but it does not answer those questions.
Manipulation is also where teleoperation matters most. A human pilot can make a humanoid look capable very quickly. Autonomous manipulation that works repeatedly, with varied objects and lighting, is a much stronger signal.