That’s where they use their fancy computer vision software to determine if the source has been tampered with.

And if they can’t determine that?

I think this is sort of where we realize that Oscar Wilde was actually the democratic candidate in the 2016 election - falsely attributed quotes have gotten out of hand and even relatively reputable sources have made this mistake... I suspect the same will be true of videos soon, your trust in the accuracy of the information will be solely tied to your trust in the organization - if you don't trust NYT you won't trust videos you see there and declare them "fake news", ditto for Fox and everyone else.

This is leading society to a very dangerous place where the truth is becoming a matter of opinion.

We've been there. It led to impartial professionals who, in person, report what they witnessed, and who made a career out of being truthful and exact.

The Bard is back again!

Yes, it's an arms race. Surely this is obviously the case?

"What if the government can't determine if a 100 dollar bill is fake?"

Answer to both questions: those who have a vested interest in detecting fakes spend more money on fake-detection mechanisms.