If you are looking for old test footage, my advice would be to check out
Trinity and Beyond which contains a lot of previous (pre '95) unreleased material.
For us with an odd sense of humor, I can also recommend watching
Atomic Cafe, mostly about the 50's perception and naivité regarding the A-bomb. A film which made my laughter about one scene often stick in my throat when I saw the next scene. It's available on YT:
It also has a great soundtrack, been looking for the record for years.
My favourite song of the movie: