Re: 99.995% is impossible
Here's a video we've already told you is a terrorist video. Is it a terrorist video?
TBH this isn't how that works. It's here's a curated set of ISIS/not videos. Here's another *different* set of ISIS videos mixed with other, which are/aren't, what's the accuracy rate? If they did it the way you say their reputation would be in tatters by the end of the day, I doubt they're that stupid.
That being said with real world data the reality is it's going to be massively inaccurate. It's entirely possible for a tool like this to exist and kinda work but I'd suggest only using it for flagging videos for a real person to look at - although as others have pointed out meat-based AI fails at this sort of thing too.