Steve Greatrex asked about copyright on YouTube (MMD 130702).

Copyright is a minefield with complex rules.  For the UK rules you
can find details on the web site http://www.prsformusic.com 
Copyright for original musical compositions is handled by the Mechanical
Copyright Protection Society (MCPS), now under the banner of the
Performing Rights Society (PRS).

Basically, copyright exists in any music whose composer is living or
has been dead for less than 75 years (used to be 50 years, but recently
extended).  The Performing Rights Society handles the copyright of the
performance of the music, whether live or from recordings.  Music
played by rolls or organ books, etc., are included.

So, your answers are:

> buying a [music] roll gave me performance rights;

a) buying a roll gives you the right to own the recording but not
the right to its public performance.

> any copyright expired 50 years after ... ...

b) Copyright of the musical composition expires 75 years after the
composer's death, but copyright remains current for the mechanical
copy of that music (whether in sheet music form or recordings: rolls,
discs, CDs, etc.).

> postings could be made if there was no commercial gain;

c) Simply not true.

> they've got the wrong piece of music anyway!

d) No comment!

Apart from the above, the question remains: who is responsible for
the Performing Rights Society copyright when the video is viewed on
YouTube?  I would have thought it is the responsibility of YouTube,
as it is they who are streaming the video online.  You are merely
providing them with the mechanical copy of the music; you're not
posting it yourself -- YouTube are doing that.  Perhaps they could
enlighten you if asked.  Their reply will be interesting to read.

John Page, UK