Don't know if the site's legit, but I believe Crass (1978-1984) are copyleft anyway. Great political music, probaby only'll become more important and seen as such in retrospect, as time goes on, like other previously-fringe bands that are now name-dropped by everyone in the mainstream (Velvet Underground, etc.) as influences. If you've never heard them, I think "Shaved Women" and "Bloody Revolutions" would be good starter songs.
Anyway, just the messengers,
-B.