... the point is that it only applies to government restrictions not private parties ...
That is simply not true. The government cannot make any law that impinges on freedom of speech. For example, it can’t pass a law that says you can’t criticize Audiogon. That would be restricting your First Amendment rights.
(Strictly speaking, the government could pass a law saying you can’t criticize Audiogon. But such a law would be unconstitutional and would not withstand scrutiny in the courts.)
And in this case we’re specifically talking about speech not religion, the press, assembly or redress of grievances.
A YouTuber opining on the Internet is, functionally, the press. He’s protected under the First Amendment. But even if it were your post - a random, one-time post - you’d still be protected.
Of course this doesn't apply outside the US. As Americans, the First Amendment is a precious gift.