Editing Images - How to change stills to 'behind the scenes'

When editing images I have noticed some say 'Still of ------ in ------', some say '---- in ----' and some say '----- behind the scenes of ------' how do you change the categories of these images? One example is that this image http://www.imdb.com/media/rm4035560704/nm3389576?ref_=nmmi_mi_all_bts_10 says it is 'behind the scenes' however it is a promotional still.