Are there any fonts in the public domain which are copyright free to use for multimedia projects such as film?

Answer 1

Yes thousands of them

Microsoft has many on their own web site.

Answer 2

Fonts, or how text appears visually, are a tool. Think of a typewriter, if an author pecks out a story, who holds the copyright, the author or the manufacturer of the typewriter?? The designers of fonts have no copyright in the works that are made using them. They do have protection against other tool makers copying their designs, as a matter of artwork or trademark.