Here’s an entertaining clip from “What’s My Line?” (as in “of work”), with Alfred Hitchcock as the mystery celebrity. Some detective work might have turned up an exact air date, but I’m too lazy for that sort of thing today. At any rate, since he’s plugging Rear Window, it’s safe to assume that this is from August or September 1954. The great man’s droll manner and indefinable charisma are very much in evidence, but notice the bespectacled wisenheimer who fancies himself a film buff. Golly, did Hitchcock, a film director as famous and recognizable as the stars he employed, really make a habit of appearing in his own movies? Tell me more, oh infinite font of arcane movie lore! Geez.