Copyright issue on internet?

According to the Archive.org website and other sources, Charade is now in the public domain due to a legal irregularity: no claim of copyright was put into the original prints, even though that copyright notices were mandatory in the US prior to 1989. This error did not become a serious problem until the introduction of VCR equipment, which meant that companies could produce retail copies without the need to pay licence fees. As a result, there are many editions of Charade on VHS and DVD, of widely varying sound and picture quality. The restored Criterion DVD edition sells, on average, for ten times the cost of most DVD releases of the film. The film was included as a bonus feature on the DVD release of its remake, The Truth About Charlie.