Facebook knew the video was doctored- it was a mainstream news story for days. They chose not to content ID it, but instead to continue spreading it. That seems deliberate.
On the other hand, there was a super-viral video about this on Twitter that was really obviously doctored. It "proved" that parts had been sped up by overlaying the video on a 7-frame-behind version of the original. Unless you paused the video this desync was only noticable in faster-moving sections, creating the illusion those sections were sped up. Not one news reporter spotted this. People like Captain Disillusionment happily spread it as fact.
If we based our decisions about what's doctored and should be blocked from spreading and what isn't on the media reporting, it'd mean treating truth as lies and lies as truth.
[1] Seriously. You can replicate the incredibly simple frame rate conversion (just blending the frames on either side) in a few lines of Python and get every single one of those artifacts out: https://www.makomk.com/2018/11/16/recreating-that-white-hous... From what I can tell this is the default setting in Sony Vegas, which is what the guy used.
The genie is out of the bottle. Unless you want a 1984 style propaganda you have to accept that media is different from 10 years ago and it'll never be the same.