It really isn't hard to find Guns N' Roses footage pre 1996.
As Loaded NightraiN has already suggested, youtube is your friend. If you want footage that you can download, I would recommend sifting through messageboards like this one prefferbly in the relevant
download sub section(s).
Also you can try programs like limewire, or other file sharing programs, although I wouldn't advise this as many viruses are usually hidden among them. You can also try sites such as dailymotion, vimeo and even google to search for video.
As I said it really isn't
that hard, just use abit of common sense and initiative.