The Youtube user in question, this "hipsterdisco" douche, notoriously neglects to credit sources. He has been doing this for YEARS. The only reason he has gotten a little better is because I have harassed him on Youtube about it, especially after your initial Soundcloud shares were taken by him and put up on Youtube with NO mention of either you or this site or even your Soundcloud account.
Having said that, I see ZERO reason for compunction regarding any shares or mirrored postings of bootlegged material (i.e. adding the tracks to the Never Heard Symphonies comp, or making a downloadable folder of the leaked tracks, etc.) PROVIDED the source of the leak is given credit accordingly at the time. And the reason for that is that as nice as it was of you to share this stuff, and as much as the community is in debt to you for giving them the opportunity to hear the material, it still doesn't belong to you.
Now, one could go to a concert and record a show without permission, and then share the show on Dime or Smithstorrents or something, and get all proprietary about it, and say "do not share elsewhere" or "do not convert to mp3" or whatever, but the fact is that while this person has a right to claim the recording itself, he has NO right to dictate if, when, where, or by who it can be shared because he never got permission from the artist in the first place before he recorded and disseminated their material...or in your case, or your sources' case, leaked it.
Therefore, this whole "manners" thing, and asking permission, is for the birds. Give credit where credit is due regarding leaks and sources, but from there it's a free-for-all considering that the only person/persons who have ANY real claim to the material is the artist and, perhaps, their record company.