Relatively technical black and white film about the Tumbler-Snapper nuclear test series of 1952, which uses footage from the Tumbler-Snapper film avaiable here on Internet Archive. The viewer must not worry should the audio drop to zero: it has been done so to censor ("sanitize") parts which may reveal still-classified information. It is also interesting to see that there are no yellow bands going up to down the screen, as happened on previously released declassified DoE films (seems that they solved the Betacam-VHS conversion problem which caused the annoying effect).
You can stream Tumbler-snapperTechnicalReport-DoeVideo0800076 free and legally on OldReel, via the Internet Archive.
Yes — it is in the public domain and can be watched and shared freely.