https://www.techdirt.com/articles/20170812/01102937985/once-...
https://www.middleeasteye.net/news/youtube-ai-deletes-war-cr...
Do they actually delete the videos? For all we know, the video is still stored on Google's servers indefinitely, there is just a flag set which blocks public access to it. If a government or UN agency asks for a copy of the video, is Google able and willing to provide it? Knowingly destroying evidence of a crime is (often) a crime; denying public access to evidence of a crime is not a crime, especially if you are still happy to provide it to the proper authorities on request.
Regarding "Destroying or covering up evidence of war crimes is, itself, a war crime", I don't believe that is actually true. Under the Rome Statute of the ICC, war crimes are crimes against article 8; destroying evidence of a war crime is not a war crime, because it is not an article 8 crime, it is a crime against article 70 ("Offences against the administration of justice"). Other international treaties against war crimes (such as the Geneva Conventions), and national laws against war crimes (such as the US War Crimes Act codified at 18 USC 2441), likewise do not consider destroying evidence of a war crime to be a war crime, instead it is a non-war crime against the administration of justice.
Sometimes we want it big enough to fight against state-level censorship; sometimes we want it small enough to obey anti-trust or privacy law.
But you are making an assumption that the average worker (probably from India) making $1 an hour, can tell the difference between newsworthy war crimes, and a snuff film.
I don't think anyone is going to get that right 100% of the time. So no, I don't really see it as a problem.
Also, lol at Youtube getting filled with war crime videos. Youtube has plenty of space.