i worked on films for several years... some of you are giving this background actor waaaay too much credit.... b/g are give less action possible unless relative to the paticular scene... i see nothing particular about her/him except the actions....
directors back then were very anal with filming.... many rehearsals were warranted so as not to waste the film..
could be a t/t...could have been filmed that way on purpose.....the dissolve in that particular spot when "it" turns to face camera is interesting...
..could have been the director himself, showing off his "must be kept secret" talky phone...egoistic cameo?....idk