THIS is what YouTube was created for!

[Guest]

The term of copyright for a particular work depends on several factors, including whether it has been published, and, if so, the date of first publication. As a general rule, for works created after January 1, 1978, copyright protection lasts for the life of the author plus an additional 70 years. For an anonymous work, a pseudonymous work, or a work made for hire, the copyright endures for a term of 95 years from the year of its first publication or a term of 120 years from the year of its creation, whichever expires first. For works first published prior to 1978, the term will vary depending on several factors. To determine the length of copyright protection for a particular work, consult [documents cited at link].

https://www.copyright.gov/help/faq/faq-duration.html

Films are works for hire. The talent is paid by the studio to make the film. So you're looking at over 95 years for new films.

Older works are subject to previous versions of the copyright laws, and determining when they expire gets tricky. Of the documents cited at link, this one is the least legalistic and technical:

Applying these standards, all works published in the United States before January 1, 1923, are in the public domain.

https://www.copyright.gov/circs/circ15a.pdf

It's a mighty goddamned long time any way you figure it.