On 14 October 1888, Louis Le Prince captured a scene in Leeds, Yorkshire, that's probably the first true moving picture. There are three Le Prince clips that predate anything by the Lumiere brothers or Edison, and yet he has never been properly credited for it. Because just before he was to present his work to the public, he vanished without a trace. At the time, there was a cut-throat race going on in Britain, France and America to crack the conundrum of making and projecting a single-lens motion picture. Are Le Prince's disappearance and obscurity the result of foul play?

For this doc, Wilkinson films himself seeking the truth about this fascinating Frenchman who settled in the Northern England city that that gave birth to innovations like the steam train, surgical gloves and Marks & Spencer. Even in Leeds, Le Prince wasn't the only film inventor, first experimenting with panoramic images, then using a 16-image contraption before patenting his one-lens camera. The grandstanding Edison was only just behind him, while the Lumieres were actually about 10th, but were better at showing their work to audiences.

Because Le Prince's story isn't part of movie history canon, UK film bodies refused to fund this documentary, even though Wilkinson presents considerable evidence from historians and museum curators. On-camera he interviews a range of experts to work out a precise timeline for the development of moving pictures, including the uncanny similarities between Le Prince's camera and modern ones. Then he moves on to theories about what happened to Le Prince, from suicide to murder.

As he digs deeper, Wilkinson includes lots of academic details and sideroads, travelling to New York (where Le Prince was due to present his invention), Memphis (where his great-great-granddaughter lives) and several places in France to piece together Le Prince's final days. Regardless of these details, the essential fact here is that Le Prince wasn't just an inventor, he was the first person to plan his shots like a present-day filmmaker. In other words, this isn't just the first moving picture, it's the first film.

L Ron Hubbard's wife Ann remembers him saying that the only way to make money without paying taxes is to create a religion. A prolific science-fiction writer, Hubbard published Dianetics in 1950, saying his theories could save people from a medical establishment that wanted to keep them sick. Over the decades Scientology has spread globally amid run-ins with tax authorities and rumours of blackmail and violence aimed at rebellious church members. And by courting celebrities like John Travolta and Tom Cruise, new leader David Miscavige has kept Scientology in the limelight after Hubbard's 1986 death.

Since no one from Scientology was willing to speak to Gibney, the film is steeply slanted. But Gibney notes the appeal of a religion that invites potential members to use what works for them and discard what doesn't. It certainly looks like an intriguing spiritual adventure, with the added benefit of superpowers, says ex-member Taylor. And as Travolta describes it, Scientology's goal is to eliminate war, criminality and insanity, and replace them with joy.

But like Mormonism, Scientology keeps the details a secret from new recruits. Only the faithful achieve the right to know what they're truly part of. And with Scientology that can take seven or eight years and donations of at least $30,000. As 35-year member Paul Haggis says, "They say give us all your money and we'll make your life wonderful." And indeed it's a matrix of thought that changes your world view, eliminating criticism until you wake up in a wave of regret, says ex-member Beghe, who adds that "the best trap is where you keep yourself in jail".

Gibney assembles this in his usual riveting style, moving through a lot of information using firsthand interviews, historical footage and animation. The film also digs into how Hubbard came up with his theories (which are essentially Freudian) and that the whole religion is a journey into his mind. But what lingers are the eerily consistent stories of abuse, black PR and legal threats, presenting a portrait of a sinister cult/corporation hybrid. And by detailing the backstage dramas involving Cruise and Travolta the film suggests that perhaps the tax authorities need to reopen their investigations.

Orson Welles was a child prodigy, directing his first Shakespeare production at 14, transforming Broadway and radio drama by 20, and at 25 writing, directing and starring in Citizen Kane, often cited as the greatest, most influential film ever made. But for the rest of his career, producers worried about his innovative style and continually recut his work. So he moved back and forth between America and Europe, looking for the best place to make movies and TV programmes. And he acted in a wide range of projects just to keep money coming in.

Filmmaker Workman includes clips from virtually every project Welles worked on, including rarely seen footage from his first film The Hearts of Age, as well as legendary unfinished projects like The Other Side of the Wind, The Deep and Don Quixote. Through all of this, Workman focusses on Welles' larger-than-life personality and his love for the works of Shakespeare. Indeed, Welles considers his Falstaff drama Chimes at Midnight (1965) to be his most important achievement.

Welles himself tells much of the story through interview footage, augmented by home movies and personal photos, plus telling comments with his long-time companion Kodar and his daughters Christopher and Beatrice. There are also knowing comments from actors and filmmakers he worked with, as well as those he inspired, with details filled in thanks to biographers like Callow. In other words, it's hard to imagine a more comprehensive look at Welles' life and career.

But of course it's tricky to maintain balance when exploring the innovation and intelligence in Welles' work. He understood why Hollywood turned its back on him (they refused to fund his films, but continued to give him awards), as his maverick approach to moviemaking echoed through his revolutionary attitudes about race equality and political fairness. It will perhaps take another 100 years to get the true measure of this remarkable man's accomplishments. As he said, "If you want a happy ending, that depends of course on where you stop your story."

With his girlfriend expecting their first child, Aussie filmmaker Damon Gameau decides to explore the effect of sugar on the average person. Abandoning his no-sugar diet, he decides to eat normal food for 60 days, making sure he gets the average 40 teaspoons of sugar per day through fruit, juices and healthy things like yogurt, muesli bars and smoothies. His caloric intake goes down and he maintains the same exercise regime. But the results on his body are dramatic, both inside and out. Even scarier are the striking changes in his moods and cravings.

To make his point, Gameau compares the effects of fat and sugar. For decades, the sugar lobby has labelled fat the ultimate dietary evil, promoting calorie-counting and vilifying carbs. But as Gameau demonstrates through his experiment, plus commentary from a range of experts, it's actually sugar that's to blame for the steep rise in obesity and diabetes, and probably also our instant-gratification culture.

Gameau is a likeable guy who maintains a slim figure eating things like bacon and pizza. He demonstrates how, with their high concentration of fruit juices, smoothies are just as bad for us as soda, and how sugar in almost all pre-prepared foods is carefully calibrated to reach that bliss point for maximum taste. This contributes to a chemical process similar to drug addiction, as the sugar rush (even if caused by artificial sweetener) creates a craving for more. And the effect of this much sugar on the body is devastating.

Of course, there are good sugars (glucose) that we need to eat, and there's also a case for taking bad ones (fructose) in moderation. The problem is that the Western diet is so anti-fat that it's out of balance. Gameau's trips into the Australian Outback and an epic journey across America continually reveal striking situations and more plain truths about the effect sugar has on our minds and bodies. And by telling the story using whizzy effects, appearances by A-listers and ultimately throwing himself right into the mix, Gameau has made a film that should be mandatory viewing.