Guided by
- https://www.kirupa.com/html5/accessing_your_webcam_in_html5.htm
- https://github.com/ilkkao/capture-video-frame/blob/master/capture-video-frame.js
- https://developer.mozilla.org/en-US/docs/Web/Guide/Events/Media_events
Basically just googling
"html use webcam" --> "capture frame from video element"