Last Night's TV: The Men Who Jump Off Buildings/Channel 4The Great Outdoors, BBC4

Everyone dies, don't they – but not everyone lives," said Dan, the subject of Alastair Cook's film The Men Who Jump Off Buildings. If you had to devise a bumper sticker to promote suicidal recklessness that would do the trick, wouldn't it? It sounds plausible enough, relegating all those of us too sensible to launch ourselves off the Trellick Tower at four in the morning to mere zombiedom. It's the sort of slogan that you need to see flashing past you in the fast lane, though, because any kind of tailback would give you too much time to question its essential premise. You might, for one thing, want to ask exactly what kind of definition of "living" was proposed here. Dan – compulsively addicted to base jumping – seemed to acknowledge at one point that it was a slightly desperate, compensatory one. "Base jumping gives me enough excitement to carry on with this," he explained, smearing tar on to a roof while doing the job that pays for his parachute. Is that really a life though – in hock to boredom for the occasional 45 seconds of terrifying adrenalin?

The Men Who Jump Off Buildings would have been distinctly dull if it had only been about the falling. It is, I'm sure, a terrifyingly galvanising thing to do, but nonetheless a bit dull to watch from the outside, over in seconds and (barring the odd bone-crunching accident) somewhat repetitive in form. What you jump from might vary – Dan had done Nelson's Column, Wembley Stadium and most of the pointy bits on the London skyline – but the jumps themselves looked a little samey, and tended to be followed by an is-that-it anti-climax, which may be connected to the urgent need to repeat the experience as soon as possible. On good nights, Dan will toss the coin on his continued existence two or even three times. His girlfriend, Tia, who he met while skydiving but who doesn't share his appetite for jabbing death in the nose, understands that she isn't likely to get him to stop anytime soon. And that was what really compelled here – the sense of a man unable to break an addiction to gambling with his own life.

"I will give it up..." said Dan, "I wouldn't say when... hopefully at the right time... because sooner or later it's going to bite me back." Statistics would suggest that it's going to be sooner, since one-in-six base jumpers are forcibly retired from the activity by a fatal accident. Dan's best friend, Neil, died six years ago while climbing a cliff in Thailand for a base jump and his most recent jumping partner, Ian, was still recovering from a horrible accident in Spain when the filming began. Ian, who relishes the foreplay to a leap almost as much as the climactic plummet itself ("It's as close as you can get to being a master criminal without committing any major crimes") recovered his nerve sufficiently to accompany Dan on a base-jumping holiday in Switzerland, where he soon provided another grisly bit of helmet-camera footage of a snarled canopy and a crunching collision with the rocks. It would have been intriguing to know whether the jump Dan made immediately following this accident (he was staring down from the cliff edge above) was even more enlivening than the others he'd made, but the question never got asked. A few hours later, Dan was filming a visit to Ian in the nearby intensive care ward, still all chirpy denial. I reckon he'll make the decision to quit when it's about five seconds too late and he's only got five seconds left in which to regret it.

Bob, the central character in Kevin Cecil's comedy The Great Outdoors, also uses his hobby to compensate for a less than enlivening day-job but has chosen a pastime in which the greatest danger is getting a nasty blister. Bob is determined to make his group into the biggest rambling club in the Chilterns, his ambitions hampered only by the fact that he's so awful he keeps driving the new members away. Some of them falter in the face of Bob's terrible jokes. Others fall by the wayside because they don't care for the fact that he dictates the conversational topics mile by mile ("OK, mile one topic... Dinner with a Beatle. Living or dead, which wife and what's the menu!"). He has one unquestioning lieutenant, Tom, and one insurrectionary one in the form of his daughter.

Bob was funny but not entirely convincing, because his lines sometimes represented him as witlessly ghastly and at other moments gave him the tart wit of a far more knowing character. "In Barnstaple, we were always prepared for the worst," said new arrival Christine, who invariably cites her previous rambling club as the perfect model of how things should be done. "You had the worst," replied Bob, "because you were in Barnstaple," which seemed to be a joke with sharper reflexes than we'd come to expect from him. A little later – also quite funnily – he was excitedly exploring a loophole in a gastro-pub's special offer ("I have discovered the secret of infinite puddings!") although this is a joke that will only really work if we think of him as an utter fool. The discrepancy may not matter in the long run because Cecil's writing can spring deceptively quiet gags on you – such as Tom's guileless explanation of his current situation: "I've been out of work before but I really want to make a go of it this time." Worth tagging along for the next mile or so, I'd say.