Last Night's TV - Imagine..., BBC1; True Stories: We Live in Public, More4

Rebel who won't play second string

It's a small thing but nevertheless always pleasing when a dog turns out to be the canine doppelgänger of its owner. At the beginning of Imagine... we were introduced, muzzle-first, to Nigel Kennedy's boisterous Weimaraner. Ears flapping, limbs flailing, tongue lolling, he leapt around making a lot of noise, slobbering and, upon meeting Alan Yentob, tried to bite his hand right off. But, back to the dog.

Just kidding! Kennedy, the human, was a predictably lively subject all by himself: all you need to do is to point a camera at him, let him off the leash and watch him run, which made Yentob a bit redundant, really. Kennedy isn't one of those interviewees who require "drawing out" – mangled soundbites simply flow out of him. When Yentob poked fun at the name Nigel – a low blow if ever there was one – Kennedy said airily: "It's a dreadful name, innit? I dropped it for a bit, but then I started missing it." (What did he call himself instead, I wonder? We never found out). Yentob then tried to drum up some controversy about the genesis of the spiky hair – "that doesn't quite entirely ring true to me!"– but Kennedy knew his story and was sticking to it. "I'm not going to pay any barber to do my 'air because you have to talk politely, you know, so I decided to do it myself. With clippers and shit."

It's been over 20 years since the violinist's recording of the Four Seasons sent him into orbit, selling over two million copies. In the wake of its success, Kennedy went low profile – partly, he says, to escape record company execs saying things like, "Yeah, more Vivaldi! Where's Vivaldi's fifth season?" – and has managed to remain so, on and off, ever since. Imagine... caught up with "Britain's most unpredictable violinist" (which seemed to be selling him a bit short) on the latest phase of his career, "in the middle of nowhere" – or Poland.

Introduced to Krakow by his wife, Agnieszka, Kennedy, 53, has been busy there "trying new shit out" – wigging out, Hendrix-style, in jazz dives, teaching his Polish collaborators words like geezer and embarking on epic jam sessions, which end behind a skip at five in the morning. The film climaxed with footage of his Polish Weekend, a showcase for his experiments with klezmer music, his conductor-less Orchestra of Life and jazz improvisations, on London's Southbank in May.

Far from being a new fad, Kennedy's love of jazz dates back to his appearance with Stéphane Grappelli at Carnegie Hall, aged 16. Warned by his tutors at Juilliard that the concert would wreck his classical career, Kennedy recalled how he initially turned Grappelli's invitation down and sat in the great violinist's dressing room polishing off a bottle of Scotch before plucking up courage and staggering on stage. There were lots of lovely stories like this – of bunking off to play football in Central Park; of making $200 in two hours busking outside Tiffany; of his "saintly" mentor, Yehudi Menuhin's gentle teaching and penchant for seaweed tablets and Scholl sandals. Most enjoyable, though, was the archive footage. In one piece, an angelic Kennedy, aged seven, sawed out "Three Blind Mice" and then revealed his near-perfect RP: "I've been playing the vahalin for around two yaahs." The mockney-Brummie hybrid gabble must have come later.

In fact, for every anecdote he told, there was television footage to go with it. Kennedy grew up with the cameras trained on his extraordinary talent; it's no wonder he escaped to Poland. After an hour in his charming company, the over-riding impression was of a man besotted with music. The hair, the clothes and the accent were revealed to be nothing more than silly distractions.

Over on More4 was We Live in Public, Ondi Timoner's astonishing documentary that won the Grand Jury Prize at the Sundance Film Festival in 2009. "The story of the greatest internet pioneer you've never heard of", it introduced Josh Harris, a rare and, it must be said, exceedingly odd, visionary. Ahead of his time, to put it mildly, he was one of the first to spot the sprawling potential of the internet, pioneering online chat and video streaming and founding Pseudo.com, the first internet television network. In the process, he became a poster boy for the dotcom decade, throwing weirdly wild parties for his modem-mates where, as one contributor put it, "supermodels wearing close to no clothes were sitting on the laps of nerds playing Doom".

Harris's masterstroke was to realise that people wanted their 15 minutes of fame, not once in a lifetime, but every day. Having sold Pseudo at the height of the boom for around $80m, he went on, in 1999, to create a capsule hotel in which 100 people lived their lives on camera for a month. When that was shut down by the police, Harris moved on, rigging up 32 cameras in his own home to live out his own life online.

Harris foresaw it all – from Big Brother to Facebook – but he also became a victim of his own visions. Here was a man who declined to visit his mother on her deathbed, preferring to send her a goodbye video via YouTube. He wound up, bankrupt, on an apple farm, trying unsuccessfully to sell his own idea of the future back to MySpace before disappearing to Ethiopia to teach basketball to orphans. An extraordinary tale of a man tragically just ahead of the curve – and, for anyone who's ever clicked refresh on their Twitter feed a little too compulsively, required viewing.