The Trailer stuff, where we are generally talking about recordings of living singers, some of whom are still working, is a potentially tricky issue as they are clearly commercial recordings made to profit from. Having said that, the artists who made the music could take a cue from Matt's 'publish and be damned' suggestion and bootleg their own albums. Given the length of time it is since the rights to the recordings have been exercised, some may feel it's a risk worth taking - whatever the potential value, in real terms, the rights have absolutely zero value to anyone, the present owners included, while they sit pointlessly gathering dust.There might even be an argument that 'reclaiming' them after so much time has elapsed is perfectly legitimate. Having said that, it's increasingly difficult to sell reissue CDs even in small runs unless its's something really sought after or special.

With the Leader recordings of traditional singers, it may be a different story. Though a small number of people may want to own copies of these albums purely for listening pleasure, I'd wager that they would be of most interest to singers and musicians, folklorists, researchers, ethnomusicologists and so on. The easiest thing here would be to make good quality vinyl rips and make the sound files available as free downloads or streams for research purposes. This could probably be done legitimately via a library or archive or less legitimately through links to Mediafire or a similar service. No physical products, no scope for making a profit.

There's a perfectly valid argument that field recordings of traditional singers, who were never singing for commercial gain in the first place, have no place in the private collection of someone who has no intention of doing anything with them - especially when the current copyright holders didn't even make the recordings in the first place. Yes, let them physically hold on to their property if that's important to them, in that no-one is looking to take custody of the master tapes or assume ownership of the rights to the recordings. But let the genie out of the bootle. Liberating a part of our shared cultural heritage may be theft, but is theft of something that is clearly of little value to the owner, and as long as no-one else tries to profit from the recordings, I really don't think there are any ethical issues at stake.

IMHO.