Just watched this on YouTube
What a movie. It's what Sci-Fi is made about and although a cheaply made production by PBS it is a great story from a book of the same name.
There are a couple of uploads if you search but the best one I found is in 480 and is watchable. You can see it here:
https://www.youtube.com/watch?v=3RJX0Gjx6mE
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My favorite: Dr. Strangelove or: How I Learned to Stop Worrying and Love the Bomb