I just shipped a 35-second explainer on how oxygen gets from the heart and lungs to the cells, and what we can do when it isn't enough. Concept: Oxygen delivery works like a train. The heart and lungs load oxygen at the station, the cells take about a quarter at the depot, and the rest comes back. When demand outstrips supply, we can speed the train up (cardiac output), add wagons (haemoglobin), fill them fuller (saturation), or cut the demand (sedation, paralysis, antipyretics). Tools: Remotion + Claude Code for the build, ElevenLabs for the voice, PubMed to check the numbers, CapCut to put the sound on. What I'd do differently: spend longer on the spec and scene cards before building. Most of my changes came after I saw the first render: bigger writing, cells turning blue or red, more wagons to make the point obvious. With a better spec, most of those would have been settled before building. I teach PICU trainees and nurses, and this is one I'll actually use.