Security Guard Spotted White Object in Empty Unit

This was submitted to us via a member of the SC Private Group. This was taken in a condominium in the east of Singapore. According to the management, the 4th floor unit has been empty for three months but security guards doing their rounds  would occasionally see a lady in white standing at the window. This video is edited to shorten the duration to where the action is and brightened for clarity.

Discussion on the group has suggested that it might be a curtain or a squatter in the unit but personnel working in the condominium has confirmed that there's not body living in the unit and there's no curtain by the window. 

So what could this be? You can see the zoom in stills below.

Zoomed in shot.

Still shot brightened for clarity.