What a lot of people don't get is that sound recordings are treated differently from most other kinds of IP, including published music (the music itself, not a recording). Most other stuff is protected for either ninety-five years from publication or 70 years after the death of the author (Exception: If said
thing was published prior to 1923, it's already public domain). Recordings, like the Ink Spots' rendition of that song, are different however.
The reason for this can be found in the U.S. Copyright Act of 1976, § 301(c):
With respect to sound recordings fixed before February 15, 1972, any rights or remedies under the common law or statutes of any State shall not be annulled or limited by this title until February 15, 2067. The preemptive provisions of subsection (a) shall apply to any such rights and remedies pertaining to any cause of action arising from undertakings commenced on and after February 15, 2067. Notwithstanding the provisions of section 303, no sound recording fixed before February 15, 1972, shall be subject to copyright under this title before, on, or after February 15, 2067.
This means that the law covers only recordings made after February 15, 1972, and all those made prior to that date would remain under state law. Before the 1976 Act, sound recordings were not covered by federal law, so this passage was intended to create a smoother transition from state coverage to federal coverage, avoiding any recordings inadvertently falling into the public domain. What this means is that under current law, all pre-02/15/1972 sound recordings will remain under state or common law until 2067, at which point they will be made public domain under the rules of federal law. I suspect the reason the guy uploaded it on archive.org as 'public domain' was because he read that pre-1972 recordings are not covered by
federal copyright law, and did not realise that this is not the same as not being covered by
any copyright law, and that the preexisting non-federal copyrights are still very much active.
It might seem safe, but people CAN get fucked hard over violations. See: The 2005 Capitol v. Naxos case, where Naxos, a distributor of 1930s classical recordings, was up against the apparent US rights-holder of some of said recordings. The judges ruled against Naxos, and declared that as the state had no explicit laws dealing with sound recording copyright, they were governed by common law. End result? The rights-holders hold the rights forever (in reality, until said common law ruling is superseded by federal law in 2067). Investigations into the laws of a number of states have found that in most, recordings are covered by common law as they were in New York, under permanent control of the rights-holders. There might be a few states where it's legal, but all it takes is one download in a state where it's illegal to be actionable.
Basically what this means is that under US copyright law, there are VERY few sound recordings that are actually in the public domain. They consist mainly of recordings released by the rights-holders themselves, recordings made by the US government (arguably, since the US gov can't hold copyrights), and various oddities anyone without real familiarity with copyright law would have trouble recognizing. Much of the stuff people incorrectly think is in the public domain is because of misinterpretation of the law, and even if they escape the notice of the rights-holders, what they are doing is in fact illegal.
For a pretty easy to understand guide to all this sound recording public domain stuff, see
this list.
