Subject: Re: UK wants to arrest, extradite US citizens...
It would not surprise me if speech that would be protected here might be subject to criminal penalties if made in other countries.

Absolutely. The 1st Amendment doesn't apply in the UK, as you pointed out. I remember a few decades ago that a British production/documentary about Jack the Ripper was not allowed because it implicated a member of the royal family. That couldn't happen here, but it did there.

John Oliver violated Canadian law in one of his shows, commenting on Canadian elections. I don't recall the details now, but evidently foreign nationals are not allowed to do that in Canada. If they chose to enforce, he wouldn't be able to travel there for the foreseeable future.

And that's just two examples off the top of my head involving 1st-world countries that are our allies. You have to play by the rules of any country you choose to visit. Our Constitution does not apply there (except as it pertains to actions by the US government against citizens, according to you a few years ago).