For filming exterior IMAX footage from inside the Space Shuttle, this black fabric shroud was one part of the draping required to limit the amount of light from inside the shuttle that reached the camera lens. The camera was mounted in the windows on a specialized bracket and this shroud was Velcroed to that mount.
NASA transferred this to the Smithsonian with other IMAX equipment in 2012.
This object is not on display at the National Air and Space Museum. It is either on loan or in storage.