Our landing page had a three-minute product demo video. It autoplayed muted, like most demo videos do. Which meant that for most visitors, it was a silent movie of a cursor clicking things.

A teammate who is hard of hearing pointed it out first, kindly. Then our analytics confirmed it: almost nobody unmuted.

So I spent an afternoon adding real captions and chapter markers. No video platform, no paid captioning service, just a file, a text editor and the HTML <track> element. Here is the whole process.

What we are building

A captions.vtt file with accurate, readable cues

A chapters.vtt file so users can jump to sections

A <video> element that loads both, with captions on by default when the video starts muted

Step 1: Get a timestamped transcript

You need text with timings, which is exactly what audio to text output gives you. I uploaded the MP4 export of the demo to an audio to text tool and exported VTT directly.…