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Derek Sivers annotates a short clip of a lone dancer at a festival, showing how a first follower turns a ridiculous act into a movement. He draws out lessons about leadership and making it easy to follow.

Arthur Keller gives a roughly half-hour crash course on environmental collapse, covering exponential growth, carrying capacity and ecological overshoot.

Matt Parker talks Numberphile through the different kinds of numbers: algebraic, transcendental, computable, normal, and beyond. It shows how few numbers we can actually name or describe.

Posy gives a short history of the computer mouse cursor, from early straight pointers to the tilted arrow, comparing Apple and Windows designs. He then explains why he designed his own cursor set and offers it as a free download.

Veritasium's Derek Muller visits NASA JPL to see the Mars helicopter Ingenuity before it was mounted on the rover. He explains how it can fly in Mars's thin atmosphere with large, fast-spinning contra-rotating rotors and low mass, and covers power and cold.

Veritasium tells the history of how imaginary numbers arose from the quest for a general solution to the cubic equation, including the duels and secrecy among Renaissance mathematicians. It argues math had to give up the requirement that it mirror reality.

Isaac Arthur's in-depth look at what it would take to settle and eventually terraform Mars. He covers the challenges and the scale of the work needed to make it a home for humanity.

Technology Connections explains why humidity matters and compares the main types of humidifiers, including evaporative and ultrasonic designs. It covers how and why you would add moisture to indoor air.

A Kurzgesagt animation walking through how a Mars base could be built and why it would be punishing, covering radiation, temperature extremes, toxic dust and the need for shielding.

NASA's animated explanation of the Curiosity rover's Mars landing, which relied on a complex automated sequence taking about seven minutes. It features NASA engineers discussing the risks before the 2012 landing.

Sabine Hossenfelder asks whether complex numbers are just a convenient tool or necessary in physics. She discusses a recent paper arguing that quantum mechanics cannot be done with real numbers alone.

3Blue1Brown illustrates how enormous the 256-bit search space is, showing how infeasible it is to find a hash or key by guessing and checking.

A step-by-step animated explanation of how SHA-256 works, from padding and message schedule to the compression function and final hash, with source code for the animations.

FortNine explains the economics of the dealership model, arguing that dealers absorb inventory risk and help manufacturers' finances. It looks at whether cars and motorcycles could be sold more cheaply without them.

Richard Feynman, in a clip from the BBC series Fun to Imagine, takes on the puzzle of why mirrors seem to swap left and right but not top and bottom.

Linkus7 explains how a community reverse-engineered The Wind Waker to predict its random number generator and beat the Sploosh Kaboom battleship minigame consistently. It includes d3 animations by Peter Schmidt-Nielsen.

Eager Space examines the practicality of putting data centers in orbit, walking through three scenarios with cost calculations and the launch cost reductions that would be required.

CGP Grey explains how the 2015 UK general election showed the flaws of first-past-the-post voting, with parties like UKIP winning many votes but few seats.

Rob Miles explains on Computerphile how language models generate plausible text and how transformers improved on recurrent networks, with a look at what comes next.

Not Just Bikes looks at the tiny microcars such as the Canta seen around Amsterdam. It discusses how they serve people with mobility issues, can use bike paths under certain rules, and where they fit in a 21st century city.

Scott Manley examines why SpaceX, Google and others are looking at orbital data centers. He walks through the economics, heat rejection and solar power arguments, with links to the Lumen/Starcloud and Google Suncatcher papers.

Technology Connections explains how automatic windshield wiper rain sensors work, using an infrared light source and total internal reflection in the glass.

A short BicycleDutch episode showing how Dutch protected intersections continue cycle paths through the junction without needing extra street width.

Kurzgesagt explains the skyhook, a rotating cable with a counterweight that could catapult spacecraft from Earth orbit toward deep space. It covers why it would make space travel cheaper and more efficient.

PBS Space Time surveys five realistic options for interstellar travel, from conventional rocket fuel to antimatter and nuclear pulse propulsion. The options rely only on known physics.

The first episode of Crash Course World History, in which John Green covers the shift from hunting and gathering to agriculture and how it shaped civilization. It is delivered fast and with jokes.

Geoff Marshall explains a running gag about London Underground stair signs claiming that the climb equals 15 floors, regardless of how many steps there actually are.

An Isaac Arthur episode on civilizations in the far future, past the Black Hole Era. It covers iron stars, Boltzmann brains, reversible computing and the idea of reversing entropy.

An RSA Animate illustrating a lecture by psychologist Philip Zimbardo on how people's perspectives on time (past, present, future) shape work, health and well-being.

Scott Manley analyzes the idea of putting data centers in orbit, prompted by Lumen Orbit's funding. He examines the claimed advantage of constant solar power against launch cost, cooling and mass.

Two Minute Papers covers a paper on speeding up fluid and smoke simulation with convolutional networks. It contrasts the approach with earlier regression forest methods.

3Blue1Brown's visual explanation of how transformers and GPT-style language models work, tracing data through tokens, embeddings and attention.

Cody's Lab builds a 200-billionth-scale model to show how far away the nearest stars are, using parallax and light speed. A short astronomy explainer on interstellar distances.

3Blue1Brown's visual walkthrough of the attention mechanism inside transformers, covering self-attention, multiple heads and cross-attention. It is chapter 6 of his deep learning series.

A PBS Infinite Series episode explaining the mathematics of quantum computers, including how qubits store complex numbers and how quantum computation differs from classical computation. Hosted by Kelsey Houston-Edwards.

Tom Scott examines why YouTubers must declare paid endorsements while TV, film and other media face no such rule, comparing regulations in the UK and US.

Science journalist potholer54 examines the claim that SARS-CoV-2 came from a Wuhan lab, tracing the sources behind it and the weaknesses in the evidence.

A PBS Space Time episode asking whether Venus would be a better colonization target than Mars. It covers Venus's habitable altitudes, floating balloon habitats, and the term surfacism.

An RSA Animate summary of Iain McGilchrist's lecture on the divided brain, arguing the brain's two hemispheres attend to the world differently and that this has shaped culture and society.

Tom Scott stands by a construction site and explains why reversing vehicles now use a white-noise hiss instead of beeping. The sound is easier to locate directionally and less annoying to neighbours.