How interactive video actually works, explained without the marketing language

Two layers run at once. The top one is picture and sound, exactly what you'd expect. The bottom one is a timed instruction track written against the timeline, closer to sheet music than to audio.

A device reads the bottom layer live while the top one plays. That's it. No AI deciding anything, no camera, nothing recorded. People assume it's far more complicated and are usually a bit disappointed when they find out it isn't.