Last Night's Television - Flight of the Conchords, BBC4; Horizon, BBC2

Still scaling comic heights

I feel I've paid my dues with Flight of the Conchords, first getting attached to them when they did a series on Radio 2. Back then, the notion that "New Zealand's fourth most popular guitar-based digi-bongo a cappella-rap-funk-comedy folk duo" might make it big in America would only have registered as one of their hapless manager's fantasies. Rob Brydon was doing the documentary voiceover and Murray (the hapless manager) was regularly phoning Neil Finn of Crowded House for career advice. Something went right, though, because HBO's first series about about two naive musicians trying to scrape a living in New York went well enough for a second series, delayed only by the fact that the group had used up virtually all their musical material in series one and had to start again from scratch.

We began, fittingly and reassuringly, with a band meeting, Bret and Jemaine responding to Murray's roll-call in an unexpectedly plush penthouse office. This, it soon becomes clear, is the result of Murray's association with a novelty hit-machine called the Crazy Doggz, whose gold discs line the wall. Worried that such managerial energies as he possesses are being monopolised by his new band Bret and Jemaine sack him, at which point Murray spitefully reveals that the two Flying Conchord's Grammy's on his office shelf are actually just pencil-sharpeners with fake labels. "I thought we won Best New Zealand artist," said an aggrieved Jemaine. "There's no such category," replied Murray scathingly. The in-joke for devotees being that along with being named Wellingtonians of the Year in 2007, the Conchords can also rank a Grammy for Best Comedy Album among their genuine awards.

If you'd come back for the songs you might have felt a little short-changed, with one pastiche Broadway lament for Murray, a short toothpaste jingle, and a song called "Angels", which had no very obvious connection to the plot. If you'd come back for the comedy, though, things were just fine, the humour still wonderfully underplayed, so that the laugh often comes a beat and a half after the punchline.

"This could make you so rich you'll be shitting money," said Greg Proops's adman, offering them a jingle for an organic women's toothpaste. "Literally, if you want," added his earnest female counterpart. Jemaine feels he's well qualified for this gig. "My father's a women's-rights activist." "Your dad? Not your mum?" said Bret. "My mum! No! My dad wouldn't allow that." Happily for us, if not for Murray, it turns out that Crazy Doggz's biggest hit is identical to a "cover version", which just happens to have been recorded several years earlier, so by the end, he's returned to his job at the New Zealand consulate, where nobody had quite got round to reading his boat-burning letter of resignation. I had a broad happy smile on my face as the final credits rolled.

Not the case with Horizon's How Violent Are You?, which isn't necessarily a bad thing, since Michael Portillo's film was, notionally at least, a serious investigation of a sombre subject. He started in Bolivia, where he attended a kind of fiesta of formalised violence in which men, women and children pair off to punch each other senseless. Portillo himself then squared off against a worryingly ancient-looking man, flailing at him wildly in order to test a resident psychologist's contention that if he was in a situation where violence was socially sanctioned he would relish it. It didn't seem to have worked, though it had released a buried aggression against the producer: "Did you enjoy it?" asked an off-camera voice as he gasped for breath. "No... fuck off," Portillo panted back.

The film finished by restaging the Milgram experiment, a psychological test of biddability in which subjects are persuaded to give increasingly painful electrical shocks to human guinea pigs. Quite how they found candidates who hadn't already heard of the Milgram experiment I'm not sure. It's been on television four or five times in the last few years, in programmes ranging from Derren Brown shows to documentaries about Abu Ghraib. I wouldn't honestly be surprised if it hadn't popped up in Coronation Street, at some point. Quite why they had was a bit of a mystery too, since the Milgram experiment doesn't really tell you anything about human propensity to violence – only about people's willingness to accept whatever a "scientist" tells them – a quality Horizon regularly exploits quite shamelessly. If I was a violent man I'd have hit my television.