Lots of movies have ended up in the public domain. Companies close, rights lapse, owners pass away, the years go by and eventually they're public property. Some familiar titles are apparently no longer "owned" by anyone: A Bucket Of Blood, Attack Of The Giant Leeches. Night Of The Living Dead, It's A Wonderful Life and Charade were PD at one point owing to overlooked or unrenewed copyrights. Many others are presumably PD either because no-one wants the damned things or no-one's willing to admit they had anything to do with them: they were useless fifty years ago and they're just as useless now.
So's Your Aunt Emma! is a creaky and staggeringly primitive Z-list "comedy" from Monogram, made in 1942 and you do end up wondering for precisely whose benefit it's been dug up, digitised and put onto YouTube (by no less than five separate people). Just 62 minutes long and containing not one shadow of a laugh - though there are innumerable later comedies at least half as long again with just as little mirth - it's a dimwitted tale of an old biddy from the sticks (ZaSu Pitts) outwitting gangsters in the big city and mistaken for a legendary criminal mastermind amidst an incomprehensible string of kidnappings and shootings, aided by a harassed reporter who's trying to get married. His Girl Friday it ain't.
Maybe Adam Sandler can put on a dress again and remake it; otherwise it's got no value to the modern world whatsoever. Director Jean Yarbrough was churning out at least five or six films a year in the 1940s, according to the IMDb; his 1943 output included something called So's Your Uncle which is unrelated to So's Your Aunt Emma! It's unmitigated nonsense and honestly not worth the YouTube bandwidth. Stupefying.