This is a very serious issue by far not limited to facebook and youtube. The problem goes much further then private companies not wanting the content on their site. Its very much motivated by a push of governments to purge terrorism propaganda and stuff that could be used to radicalize people.
The best example is, or better was, reddits /r/syriancivilwar. The subreddit collected all and every information available on the conflict, from every side. This brought them in direct conflict with reddit admins, who banned multiple users for linking to terrorism propaganda, namely ISIS videos and AMAQ statements, the ISIS news agency. The subbredit is now a shell of its former self because its reduced to a propaganda platform for factions which are socially acceptable, instead of a place to document the war and its atrocities.
It however doesnt stop there. The content wasnt hosted at reddit but literally anywhere where there is a hope it might not be immediately taken down. From piracy favored streaming services to archiv.org mirrors. Which all get taken down for distributing terrorism propaganda instead of violating the TOS.
When you hear about terrorism propaganda, there is a good chance we are talking about not just evidence of warcrimes, but also material that is important to understand how people can get radicalized. And how to counter that propaganda. People at risk of radicalization can still access the material while the public as a whole looses the insight into the mind of those people entirely. And the people at risk drift off into echo chambers. And for a lack of information we are doing nothing to counter that propaganda, quite the opposite. I doubt the media at large could have done ISIS a bigger favor by their coverage of focusing simply on the barbarism of the videos. They missed the point entirely, the barbarism was very much a part of ISIS propaganda. The reporting was great for getting views, but only reenforced the people who already entered the echochambers. And hoping on a purely military solution sounds absolutely naive to me. Its very much a task for society as a whole to watch out that people dont drop into those echo chambers and get radicalized.
Framing this issue as "AI gone wrong" misses the point entirely. The content would also have been deleted by a human. And with the given political development, its not overly pessimistic to assume that people publicly hosting content will be forced to remove any such content immediately or face prosecution. Which only helps with getting reelected for signaling to combat terrorism instead of actually doing anything against terrorism.
Not to sound overly pessimistic, but the situation looks really dire to me. I had hoped that we as a society had learned our lesson about book burning. And the issue is not a new one. Mein Kampf is still not readily available in Germany for the "fear that it might turn people into nazis". Serdar Sommuncu made the only reasonable thing here and started touring Germany reading from Mein Kampf as well as famous propaganda speeches to show how ridiculous they are. There is nothing special about them. There isnt some hidden insight in those books that turn people into Nazis. But our treatment of them might convince people at risk that there has to be something about them, or they wouldnt be banned in the first place. I fear very much the same development from the array of far right terrorists with their manifests. Instead of the rambling of lunatics they are it gets treated as something that is dangerous as it apparently might convince people.