For those interested but who can't stream it, I appear to have found it online. A direct Google search limited to videos over 20 mins found endless reaction videos and "making of" documentaries etc. So I tried alternatives.
I don't want to give a direct link in case of copyright issues but if you happen to find yourself on archive.org and click on movies and search for "Where Eagles Dare" and scroll down a bit, you may find it
It seriously is an absolute classic and its making is quite a story.
Edit: I added the bit where you search for the movie on archive.org

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