I strongly oppose this practice, as it appears on this page (and I assume similarly-tagged pages):http://imslp.org/wiki/The_Firebird_%28S ... y,_Igor%29
I understand that IMSLP wants (and must) protect itself from any future copyright infringements, and that it is (obviously) not responsible who downloads its content and is (equally obviously) responsible for informing visitors of the website about whether or not there might be some problems downloading this score in their country, but I don't agree in the way it's been carried out.
What I suggest is the following: instead of having a fat white arrow (as in any other page: http://imslp.org/wiki/Piano_Trio_No.1,_ ... William%29
) we could have a fat white arrow, tinted red
or something like that - to make it distinctly DOWNLOADABLE (as opposed to a fat X showing it's not downloadable), but also distinctly POTENTIALLY PROBLEMATIC - the red tinting would be an instant reference to the red-coloured text in the copyright information which would clarify why this score could be problematic, and where.
I also understand that the main deal with the US-1923 pieces is that they are hosted on a different server, but I think this is a) a technical detail which concerns the legal aspect of IMSLP and potential suers etc, b) a practical issue with regards to problems raised as of (a), and c) a detail in the larger image: that this file is NOT entirely freely available in the public domain pretty much everywhere, and as such may be illegal to download in certain countries.