What's the deal with the popcorn button?

From a channel Lumen includes in full: Alec Watson takes ordinary household technology (heat pumps, dishwashers, light bulbs, car chargers) and explains how and why it works in long, carefully reasoned, demonstrated explainers; famously thorough and quick to publish corrections.

A 14-minute video from Technology Connections's catalogue; the title names its topic.

Video by Technology Connections, played through YouTube's embedded player.