Hi there Dmitry.
Firstly you are correct.
There are many recordings of Nazareth which have never been seen or heard.
I have some audio recordings from numerous tours and have tried to share some of them on this website but I have to be careful.
As for videos, again I have to be aware of copyright laws before posting anything but most of the time the videos on this website are from my old VHS tapes so are not as good quality as you would expect but remember I was actually an active member of Nazareth at this time so I didn’t pay too much attention to preserving them.
Presumably we paid someone else to do that but perhaps they didn’t care enough?
I understand your frustration and totally agree with you but alas there is nothing I can do to locate the better quality recordings.
Someone, somewhere may have them but I do not.
Stay safe and best wishes from Scotland.