Thanks to the Internet, television borders, like national ones, have grown blurry. A program broadcast in one country can now be seen the same night in another, at least in YouTube-size segments. A good case in point is “Dispatches: Undercover Mosque,” a secret investigation by Britain’s Channel Four into anti-democratic, anti-Western preaching in reputedly moderate British mosques. The documentary, which was shown in Britain on Monday, was linked via YouTube on the Drudge Report the following day.

Radical Islam in Britain will also be featured tomorrow night on “CNN: Special Investigations Unit,” a new series which sounds like something involving David Caruso, designer sunglasses, and murdered fashion models. In fact, this episode, “The War Within,” stars Christiane Amanpour, and while it would be going too far to call it an unflinching look at Muslim extremism, it does at least look at it. But let’s not give Ms. Amanpour, arguably the most famous female journalist in the world, too much credit. Oriana Fallaci lamented before her death last year that she had come so late to the most important story of her lifetime. She was talking about the growth of Islamic radicalism in Europe, and she was referring to its beginnings in the 1970s.

Now in 2007, we have Ms. Amanpour, chicly turned out in dark glasses and a long dark coat, announcing at the outset that London, which has been not only her home but also her “refuge” from conflicts overseas, is itself embattled, a site of conflict and suicide bombings and fear. Unfortunately, little history or context for the eruption of this problem is provided. A massive, highly politicized Muslim population is just suddenly there, in Britain. There is no reference to the fatwa against author Salman Rushdie in 1989, when there was widespread rioting by British Muslims, let alone to the notorious 1968 “Rivers of Blood” speech by the maverick Conservative politician Enoch Powell, in which the issue of immigration was placed dramatically on the front burner of English politics before being swiftly removed for the next three decades.

Ms. Amanpour appears to interview a wide range of people, Muslim and non-Muslim, but this is somewhat illusory. She interviews a fair number of Muslims and a couple of non-Muslims, primarily Alan Craig, a Christian city councillor opposed to the football stadium-size “mega-mosque” being planned for East London. (To him she says: A lot of this sounds like, I’m sorry to say, white middle class fear, and anger, of Muslims right now.”)

What she doesn’t do is interview other British immigrants about the Muslim situation. Indians, say. There are a lot of them in Britain, and I suspect they would be quite articulate on the subject. Or Chinese. Or Russians. Or West Indians. Or — you name it. All these people are kept in the background, part of Britain’s “rich multicultural fabric,” to be heard from on a more convenient occasion. Instead, the equation becomes either British whites versus British Muslims, or radical Muslims versus moderate Muslims, with white people looking on. Consciously or not, the effect is misleading and subtly racist — against white Britons.

Nonetheless, “The War Within” provides the viewer with a lot of information about the more controversial aspects of Islam in Britain today, and for that we should be grateful. We see Muslims protesting Pope Benedict’s remarks about Muhammad outside Westminster Cathedral, and the astonished reaction of the Christians as they emerge from the service inside. Tough questions are asked of various hotheads who call for the implementation of Sharia law. Ms. Amanpour interviews Aki Nawaz, a Muslim rapper with a song about building a dirty bomb (“A suitcase of Semtex, a mobile phone trigger / Blow them all to hell for a million dollar figure”). She later refers to him as being “on the cultural cutting-edge,” which will make a nice blurb if he ever writes a book.

Hanif Qadir, a genial Muslim youth-worker in London’s East End, reveals that a minority of students, both Muslim and non-Muslim, think that “blowing people up is quite cool.” Nonetheless, he believes that, if the Koran is interpreted correctly, Islam and Britishness can be compatible. They certainly seem to be in his case.

Whether or not the Koran sanctions violence is explored. At a debate between moderates and radicals at Trinity College in Dublin, a young Muslim speaker gets enthusiastic applause when he refers to Islamism as “not an ideology, but a mental illness.” But the audience applauding is Irish. Another speaker, challenged to produce evidence of Koranic calls for violence, promptly cites Chapter Nine, Verse 29: “Fight those who do not believe in Allah, and in the Hereafter.” Another Muslim moderate points out that one can find all sorts of incitements in most holy books, including the Bible.

“No one knows who will win Britain’s battle for Islam,” Ms. Amanpour concludes at the end of the program, reinforcing her thesis that the issue is a civil war within the religion itself. In doing so, she consigns the rest of the population to passivity — to sitting back and watching the radicals and moderates duke it out. Perhaps Ladbrokes will offer odds on the outcome, since the British will bet on almost anything. At least that way they’ll feel they’re getting involved.

“Dispatches: Undercover Mosque,” the Channel Four documentary (Ms. Amanpour’s sister, Lizzie, is a producer for the channel) is much more in-your-face and upsetting. Mai Yamani, a Saudi woman who emphatically disagrees with Islamic fundamentalism, states the program’s central thesis: Saudi Wahhabist teachings have been exported throughout the world, “from Kosovo to Jakarta and to the United States and Great Britain, supercharged with oil money … It’s like a wave of teachings hitting the shores of Western countries.”

Much of “Undercover Mosque” was filmed with a hidden camera. The sound is clear, but the footage is often shaky and tentative. Ironically, this is now the predominant style for hip documentary filmmaking, which affects a nervous, frantic style. Here you have the real thing — it’s nervous and frantic because it has to be. The preachers shown, including an African-American convert, are jaw-droppingly explicit in their revolutionary plans for Britain and the world.

One, Dr. Ijaz Mian, at the Regents Park Mosque in London, official seat of “moderate” Islam in Britain, talks openly about his desire to see Saudi-style religious police operating in the United Kingdom. He urges Muslims to wait until they are sufficiently numerous to make Britons surrender: “Hands Up!” Another predicts jihad will be waged against all nonbelievers and a British Islamic state established, with the flogging of drunkards, chopping off of thieves’ hands, and jihad against non-Muslims all on the menu. “You have to live like a state within a state until you take over,” he says. Women are “deficient,” and should be marriageable before puberty because Muhammad himself married a nine-year-old. The animus against homosexuals and Jews is particularly virulent, meaning not merely condemnation, but explicit calls for their (eventual) murder. One imam even mimics a throat-cutting.

Is this, as Muslim spokesmen have charged, media sensationalism? Have their remarks been taken out of context? It’s hard to imagine what context could possibly render them benign. Like CNN’s “The War Within,” the BBC’s “Undercover Mosque” is in some ways most remarkable not for what is said, but for what is shown: The growing number of neighborhoods, towns, and cities where veiled women and bearded men proliferate while the pale British faces of yore recede. Neither program touches on one great irony: Having largely turned their backs on Christianity and embraced secularism, the British (like most Europeans) must now grapple with another, far more fierce religious ideology, and this time someone else’s — on their own land.