Sites for sharing and/or downloading aircheck recordings

[richard black]

I'm aware of the legalities of this (as in, it's usually not!) but have a very specific reason for asking: does anyone know of any sites where I might be able to trace a live recording (audio and possibly video too) of a concert by a significant pianist from Moscow, approx. 1976? We know a video or film recording was made of the event, though we don't know by whom (possibly a TV station), and are just trying to trace any source. When I say 'we' I include close associates of the pianist (now dead) who are keen to get hold of the recording, if it exists. Excuse the 'cloak and dagger' aspect of this request but I don't want to give more details in public.

Thanks!