zeph’s pop culture quiz #60

A man is sitting in the cinema. Which movie is he watching? Mind, I am not asking from which film the screenshot is taken, who the man is, what he has done, or not done … although you may have to find out all that before you can answer the question.
    Simply leave a comment with your educated guess—you can ask for additional hints, too. [Leaving a comment is easy; just click the ‘Leave a reply’ at the end of the post and fill in the form. If it’s the first time you post a comment, it will be held for moderation. But I am constantly checking, and once I’ve approved a comment, your next ones won’t be held, but published immediately by the system.]

UPDATE (01 January 2019):
All right, Velvet just recently revived this, yet unsolved, installment of zeph’s pop culture quiz. It already has been found out, or guessed, that the man in the above screencap is watching a Hitchcock-movie. Velvet guessed „Rear Window,“ but I’m afraid it is not, and asked for a ‘damn hint’ if she is wrong. So, here are new hints, but I do not want to make it too easy ;) So the hints are going towards the movie within the Hitchcock-movie is shown. :) During the movie show our above protagonist attends, a man is murdered in the cinema. When the dead body is found, a book is also discovered (see new screencap below). The book’s, well, ‘title’ is a part of the title of the movie in which the murder takes place. Incidentally, or not so incidentally, the book’s ‘title’ is the name of the circuit of cinemas which for the first time showed the Hitchcock-movie in question. Said cinemas circuit also was a part of the Hitchcock-movie’s production company. From here on it still is a bit of work, conceded, but remember, Alphabet Inc.’s subsidiary Google is your friend …

UPDATE and SOLUTION (09 January 2019):
A couple of days ago Maddieman over on facebook solved the riddle—congratulations!—thanks to the help of the BBC who over the christmas days did a rerun of the movie in which the movie in question is viewed. The man in the first screenshot is Alexander Bonaparte Cust (Donald Sumpter). His initials read A.B.C. … and the screenshot is from „The ABC Murders“ (Grieve 1992), starring the incomparable David Suchet as Hercule Poirot. The book found in the cinema in the second screenshot is an ABC railway guide. The movie Mr Cust watches in the cinema is „Number Seventeen“ (Hitchcock 1932). The production company of said movie was the Associated British Picture Company (ABPC), formed in 1927 by merging a couple of companies, among those the ABC Cinemas circuit …