why questions

Jon Gjengset's long live-coding stream explains Rust's Pin and Unpin types: why they exist, how they work, and how they connect to futures and async/await. It also covers moving from pre-pinning code to the new model.

A three-minute Emacs Rocks screencast by Magnar Sveen demonstrating paredit, which edits Lisp code structurally as a tree of s-expressions rather than characters.

Phoenix creator Chris McCord builds a real-time Twitter-style app live with Phoenix LiveView 1.5 in about 15 minutes. It shows interactive, real-time updates without writing JavaScript.

A motorcycle safety video on the SMIDSY (sorry mate, I didn't see you) accident, explaining the perception and optical illusion that makes drivers fail to see riders, and how riders can spot the signs and avoid it.

A University of Michigan Medicine demonstration of building a cheap DIY air purifier from a box fan and a HEPA or high-MERV filter using hardware-store parts. It explains why this helps against dust, smoke and viruses and ties it to local air quality readings.

A beginner-focused tutorial on freehand knife sharpening with a single stone, aiming for a shaving-sharp edge in about five minutes.

James Hoffmann demonstrates his AeroPress technique with a short recipe: 11g of coffee, 200g of just-boiled water, a 2-minute immersion, then a press. He explains why he skips rinsing, preheating and inverting.

Lock-picking YouTuber Bill Johnson (BosnianBill) explains how to choose a high-security lock and why, showing examples and comparing designs. It covers what makes some padlocks more pick-resistant than others.

Big Clive shows how to pick up discarded disposable vape devices from the roadside and extract the rechargeable lithium cells inside. He explains why these devices contain the same circuitry as rechargeable ones and how to reuse the cells.

A short video advising how to handle a police stop by politely refusing searches and not answering questions, citing Fourth and Fifth Amendment rights.

A woodworker shows how his table saw accident happened, why it happened and how to avoid a similar one. He describes severe hand lacerations from a blade contact.