Check out his LinkedIn profile - https://www.linkedin.com/in/patrickshyu - from the projects he describes there, seems like he can back it up. And what's wrong with telling people you're an "ex googler/facebook"? If that's the experience you have to share, fair enough.
It's a running joke in the channel. "Hi welcome to my channel TechLead, with your host The TechLead who's an ex-google and now an ex-facebook tech lead"
From what I can gather the guy is going in on satirical comedy. Specifically in the way we tend to evangelise these big tech companies and those who work for them.
Sometimes his delivery is so deadpan that I get an odious vibe from it. But it does seem that he’s not serious and is using his previous status as a part of the humour.