Yeah, if it's considered educational, it will usually stay up. Also, if you allow Youtube to put a content warning on it, even if it isn't that educational, you have a good chance of them not pulling it. For instance, Caligula from 1979, has been up for a long time, and from 2:07 - 2:18, it's basically a hardcore porn -
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Same thing with many 70's horror films up now.
You can also dig up the Budd Dwyer tape, Faces of Death, various "mondo" style tapes from the 70's like "Shocking Asia", which was considered shocking mainly because it showed a early sex change at 55 minutes in -
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Youtube goes in waves. Sometimes strict, sometimes loose.