I can fully understand skepticism, however I'd like to point out a few reasons as to why I find the words these people are saying more reliable and trustworthy than the Chinese Government:

1. It's the Chinese Government, their most recent scandal and outright lie was covering up leaked drone footage of a concentration camp.
2. Some of the people (Including this person) criticized the Chinese Government, if they are in China at the time of the recording, they just sang their own death sentence. If they aren't in China and this is all faked, then they just ensured they'll never ever return to China.
3. The sheer magnitude of leaked videos showing that it's a lot worse than the Chinese Government is saying it is. There's a new leaked video coming out every couple of hours. Footage of overflown hospitals, footage of medical professionals losing their shit. These could well all be actors, and it could be filmed on a set. But there's a lot more of them than I'd of expected if this is some sort of smear campaign.
4. Who benefits from these videos? Aside from the small amount that they'd make from youtube revenue (which is likely next to nothing considering how easy it is to be automatically demonetized by youtube) What would somebody gain from lying about this? In a matter of weeks they'd be proven liars if all was well, so what would they gain?

I'm still not taking these leaked videos as gospel, but I'm certainly going to trust them more than whatever bullshit the Chinese Government is peddling.